diff --git a/02_MENT/Testat/main_02_MENT.cpp b/02_MENT/Testat/main_02_MENT.cpp
index 7187d34..5ca37c4 100644
--- a/02_MENT/Testat/main_02_MENT.cpp
+++ b/02_MENT/Testat/main_02_MENT.cpp
@@ -19,6 +19,7 @@ void printPascalString(PascalString s) {
 }
 
 PascalString bitwiseDualOr(PascalString a, PascalString b) {
+
     PascalString shortString = a.length <= b.length ? a : b;
     PascalString longString = a.length <= b.length ? b : a;
     
diff --git a/03_FLOW_a/MP/build.sh b/03_FLOW/MP/build.sh
similarity index 100%
rename from 03_FLOW_a/MP/build.sh
rename to 03_FLOW/MP/build.sh
diff --git a/03_FLOW_a/MP/main_mp2_FLOW_a.cpp b/03_FLOW/MP/main_mp2_FLOW_a.cpp
similarity index 100%
rename from 03_FLOW_a/MP/main_mp2_FLOW_a.cpp
rename to 03_FLOW/MP/main_mp2_FLOW_a.cpp
diff --git a/03_FLOW_a/Testat/build.sh b/03_FLOW/Testat/build.sh
old mode 100755
new mode 100644
similarity index 100%
rename from 03_FLOW_a/Testat/build.sh
rename to 03_FLOW/Testat/build.sh
diff --git a/03_FLOW_a/Testat/main_mp2_FLOW_a.cpp b/03_FLOW/Testat/main_mp2_FLOW_a.cpp
similarity index 100%
rename from 03_FLOW_a/Testat/main_mp2_FLOW_a.cpp
rename to 03_FLOW/Testat/main_mp2_FLOW_a.cpp
diff --git a/03_FLOW_b/build.sh b/03_FLOW_b/build.sh
deleted file mode 100644
index 844f053..0000000
--- a/03_FLOW_b/build.sh
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/bash
-clang++ -std=c++14 -o controlFlowIntr main_ISR.cpp
diff --git a/03_FLOW_b/controlFlowIntr b/03_FLOW_b/controlFlowIntr
deleted file mode 100644
index dcccacc..0000000
Binary files a/03_FLOW_b/controlFlowIntr and /dev/null differ
diff --git a/03_FLOW_b/main_ISR.cpp b/03_FLOW_b/main_ISR.cpp
deleted file mode 100644
index 8f87b34..0000000
--- a/03_FLOW_b/main_ISR.cpp
+++ /dev/null
@@ -1,27 +0,0 @@
-// file main_ISR.cpp
-#include <iostream>
-#include <signal.h>
-#include <unistd.h>
-
-volatile int j;
-
-//extern "C" {
-void ISR(int iarg){
-  std::cout << "ISR j=" << j << "\n";
-}
-//}
-
-void install_ISR(void){
-  signal(SIGUSR1, ISR);
-}
-
-int main(int argc, const char * argv[]) {
-  std::cout << "process ID = " << getpid() << "\n";
-  install_ISR();
-  for(int i=0; i<300*1000*1000; i++){
-    i= i +10; i-=10; j=i;
-  }
-  std::cout << "done.\n";
-  return 0;
-}
-
diff --git a/03_FLOW_b/run.sh b/03_FLOW_b/run.sh
deleted file mode 100644
index b4b5f7d..0000000
--- a/03_FLOW_b/run.sh
+++ /dev/null
@@ -1,9 +0,0 @@
-#!/bin/bash
-./controlFlowIntr &
-echo $!
-sleep 1
-kill -SIGUSR1 $!
-sleep 1
-kill -SIGUSR1 $!
-kill -SIGUSR1 $!
-
diff --git a/03_FLOW_c/AP2-dc.cpp b/03_FLOW_c/AP2-dc.cpp
deleted file mode 100644
index 5a545b3..0000000
--- a/03_FLOW_c/AP2-dc.cpp
+++ /dev/null
@@ -1,239 +0,0 @@
-// based on http://www.stroustrup.com/dc.c
-// by Bjarne Stroustrup
-// The desk calculator
-// pp 107-117, sec 6.1, A Desk calculator
-// No guarantees offered. Constructive comments to bs@research.att.com
-
-
-/*
- expr_list:
-	expression PRINT	   // PRINT is \n
-	expression PRINT expr_list
- 
- expression:
-	expression + term
-	expression - term
-	term
- 
- term:
-	term / power
-	term * power
-	power
- 
- power:
-    power # primary         // char '^' produces problems with terminal input
-    primary
- 
- 
- primary:
-	NUMBER
-	( expression )
- 
- 
-while statt for
-erweitern um o,i oder HexaDezimal mit &, |, x,
- */
-
-
-#include <string>
-#include <cctype>
-#include <iostream>
-
-using namespace std;
-
-int no_of_errors;	// note: default initialized to 0
-bool doPrintCalculations = true;
-
-
-unsigned int error(const char* s)
-{
-    no_of_errors++;
-    cerr << "error: " << s << '\n';
-    return 1;
-}
-
-enum Token_value {
-    NUMBER, // '0' ... '9'
-    PLUS='+',	MINUS='-',	MUL='*',	DIV='/',
-    PRINT='\n',	POWER='#',	LP='(',		RP=')'
-};
-
-Token_value global_token = PRINT;
-unsigned int number_value;
-
-unsigned int asciToInt(string string_value){
-    unsigned int result = 0;
-    for(size_t i=0; i<string_value.length();i++){
-        result *= 10;
-        result += string_value[i] - 48;
-    }
-    return result;
-}
-
-Token_value get_token()
-{
-    char ch;
-    
-    do {	// skip whitespace except '\n'
-        if(!cin.get(ch)) {error("EOF"); exit(1);} //return curr_tok = END;
-    } while (ch!='\n' && isspace(ch));
-
-    switch (ch) {
-        //case ';':
-        case '\n':
-            return global_token=PRINT;
-        case '*':
-        case '/':
-        case '+':
-        case '-':
-        case '(':
-        case ')':
-        case '#':
-            return global_token=Token_value(ch);
-        case '0': case '1': case '2': case '3': case '4':
-        case '5': case '6': case '7': case '8': case '9':{
-            // the easy way: cin.putback(ch);
-            // the easy way: cin >> number_value;
-            string string_value;
-            string_value = ch;
-            while (cin.get(ch) && isdigit(ch))
-                string_value += ch;	// string_value.push_back(ch); // to work around library bug
-            cin.putback(ch);
-            number_value = asciToInt(string_value);
-            return global_token=NUMBER;
-        }
-        default:
-            error("bad token");
-            return global_token=PRINT;
-    }
-}
-
-
-unsigned int expression();	// cannot do without (indirect recursion)
-
-
-unsigned int primary()		// handle primaries
-{
-    Token_value current_token = get_token();
-    
-    switch (current_token) {
-        case NUMBER:{
-            unsigned int v = number_value;
-            get_token();        // proceed global_token to next token (i.e. operator or '\n')
-            return v;
-        }
-        case LP:{
-            unsigned int e = expression();
-            if (global_token != RP) return error(") expected");
-            get_token();		// eat ')' in order to proceed global_token to next token
-            return e;
-        }
-        default:
-            return error("primary expected");
-    }
-}
-
-unsigned int power()		// 2 ^ 3
-{
-    unsigned int left = primary();
-    unsigned int right = 0;
-    
-    for (;;)
-        switch (global_token) {
-            case POWER:{
-                right = primary();
-                if (doPrintCalculations) printf("%u # %u\n", left, right);
-                unsigned int base = left;
-                left = 1;
-                for (int i=0; i<right; i++)
-                    left *= base;
-                break;
-            }
-            default:
-                return left;
-        }
-}
-
-
-unsigned int term()		// multiply or divide
-{
-    unsigned int left = power();
-    unsigned int right = 0;
-    
-    for (;;)
-        switch (global_token) {
-            case MUL:{
-                right = power();
-                if (doPrintCalculations) printf("%u * %u\n", left, right);
-                left *= right;
-                break;
-            }
-            case DIV:{
-                if ((right = power())) {
-                    if (doPrintCalculations) printf("%u / %u\n", left, right);
-                    left /= right;
-                    break;
-                }
-                return error("divide by 0");
-            }
-            default:
-                return left;
-        }
-}
-
-/*
-unsigned int ops_level_a()		        // e.g. add or subtract
-{
-    unsigned int left = ops_level_b();  // e.g. multiply or divide (which in turn calls ops_level_c() immediately)
-    unsigned int right = 0;
-    
-    for (;;)
-        switch (global_token) {
-            case TOKEN_LEVELA_1:{
-                right = ops_level_b();  // e.g. multiply or divide
-                left = left TOKEN_LEVELA_1 right;
-                break;
-            }
-            case TOKEN_LEVELA_2:{
-                right = ops_level_b();  // e.g. multiply or divide
-                left = left TOKEN_LEVELA_1 right;
-                break;
-            }
-            default:                   // an operator of another (lower) level, or \n
-                return left;           // there is no further operator (and operands) of this level
-        }
-}
-*/
-
-unsigned int expression()		// add or subtract
-{
-    unsigned int left = term();
-    unsigned int right = 0;
-    
-    for (;;)				// ``forever''
-        switch (global_token) {
-            case PLUS:{
-                right = term();
-                if (doPrintCalculations) printf("%u + %u\n", left, right);
-                left += right;
-                break;
-            }
-            case MINUS:{
-                right = term();
-                if (doPrintCalculations) printf("%u - %u\n", left, right);
-                left -= right;
-                break;
-            }
-            default:
-                return left;
-        }
-}
-
-int main()
-{
-    while (cin){
-        //cout << " > ";
-        cout << expression() << '\n';
-    }
-    return no_of_errors;
-}
diff --git a/03_FLOW_c/build.sh b/03_FLOW_c/build.sh
deleted file mode 100644
index 3674a68..0000000
--- a/03_FLOW_c/build.sh
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/bash
-clang++ -std=c++14 -o dc.out AP2-dc.cpp
diff --git a/04_UDEF/MP/main_04_UDEF_e.cpp b/04_UDEF/MP/main_04_UDEF_e.cpp
index cc84326..a9afe15 100644
--- a/04_UDEF/MP/main_04_UDEF_e.cpp
+++ b/04_UDEF/MP/main_04_UDEF_e.cpp
@@ -1,30 +1,20 @@
-// file main_04_UDEF_e.cpp
 #include <iostream>
 #include <algorithm>
 
 const int bitsPerOctet = 8;
 
 struct BinaryOctet {
-public:
-    bool evenParity;   // set to true if number of '1' in bitsAsDigits is even, false otherwise
-    char bitsAsDigits[bitsPerOctet]{}; // bit values as chars
-    BinaryOctet();
-    BinaryOctet(int x);
-    BinaryOctet(const BinaryOctet &) = default;
-    BinaryOctet &operator=(int const &a);
-    const BinaryOctet operator--(int);
-    const BinaryOctet operator-(BinaryOctet a);
-    const BinaryOctet operator+(BinaryOctet a);
+    bool evenParity;
+    char bitsAsDigits[bitsPerOctet]{};
+    BinaryOctet(int x = 0);
+    BinaryOctet(const BinaryOctet&) = default;
+    BinaryOctet &operator=(int &a);
+    BinaryOctet operator--(int);
+    BinaryOctet operator-(BinaryOctet &a);
+    BinaryOctet operator+(BinaryOctet a);
+    BinaryOctet operator/(BinaryOctet &a);
 };
 
-BinaryOctet::BinaryOctet() {
-    for (char &bitsAsDigit : bitsAsDigits) {
-        bitsAsDigit = '0';
-    }
-    evenParity = true;
-}
-
-
 BinaryOctet::BinaryOctet(int x) {
     for (char &bitsAsDigit : bitsAsDigits) {
         bitsAsDigit = '0';
@@ -43,41 +33,43 @@ BinaryOctet::BinaryOctet(int x) {
     }
 
     evenParity = i % 2 == 0;
+    //std::cout << evenParity << std::endl;
 }
 
-
-bool operator!=(BinaryOctet a, BinaryOctet b) {
-    if (a.evenParity != b.evenParity) return false;
-    for (int i = 0; i < bitsPerOctet; ++i) {
-        if (a.bitsAsDigits[i] != b.bitsAsDigits[i]) return false;
+BinaryOctet &BinaryOctet::operator=(int &a) {
+    std::string tmp = std::to_string(a);
+    for (int i = 0; i >= tmp.length(); i++) {
+        bitsAsDigits[i] = tmp[i];
     }
-    return true;
+    return *this;
 }
 
-
-//TODO: this method
-const BinaryOctet BinaryOctet::operator--(const int) {
-    return operator-(1);
+BinaryOctet BinaryOctet::operator--(int) {
+    return operator-(*new BinaryOctet(1));
 }
 
-//FIXME: returns wrong result
-//using complement method here
-const BinaryOctet BinaryOctet::operator-(BinaryOctet a) {
+BinaryOctet BinaryOctet::operator-(BinaryOctet &a) {
     BinaryOctet result;
-    //reverse a
-    for(int i = 0; i <= bitsPerOctet; i++) {
-        a.bitsAsDigits[i] = a.bitsAsDigits[i] == '0' ? '1' : '0';
+    bool over = false;
+    for(int i = bitsPerOctet - 1; i >= 0; --i) {
+        int tmp;
+        int aI = a.bitsAsDigits[i] - '0';
+        int bI = bitsAsDigits[i] - '0';
+
+        if(over) tmp = bI - aI - 1;
+        else tmp = bI - aI;
+        over = false;
+
+        if(tmp < 0) {
+            over = true;
+            tmp = tmp + 1;
+        }
+        result.bitsAsDigits[i] = static_cast<char>(tmp + '0');
     }
-    a + 1;
-
-    result = *this + a;
-    std::cout << result.evenParity << std::endl;
-
     return result;
 }
 
-
-const BinaryOctet BinaryOctet::operator+(BinaryOctet a) {
+BinaryOctet BinaryOctet::operator+(BinaryOctet a) {
     BinaryOctet result;
     bool over = false;
     for (int i = bitsPerOctet - 1; i >= 0; --i) {
@@ -104,23 +96,22 @@ const BinaryOctet BinaryOctet::operator+(BinaryOctet a) {
     return result;
 }
 
-
-BinaryOctet operator/(BinaryOctet a, BinaryOctet b) {
+BinaryOctet BinaryOctet::operator/(BinaryOctet &a) {
     BinaryOctet result;
 
+
+
     return result;
 }
 
-
-BinaryOctet &BinaryOctet::operator=(int const &a) {
-    std::string tmp = std::to_string(a);
-    for (int i = 0; i >= tmp.length(); i++) {
-        bitsAsDigits[i] = tmp[i];
+bool operator!=(BinaryOctet a, BinaryOctet b) {
+    if (a.evenParity != b.evenParity) return false;
+    for (int i = 0; i < bitsPerOctet; ++i) {
+        if (a.bitsAsDigits[i] != b.bitsAsDigits[i]) return false;
     }
-    return *this;
+    return true;
 }
 
-
 BinaryOctet doCalculation(BinaryOctet a, BinaryOctet b) {
     BinaryOctet result;
     for (; a != b; b--) {
@@ -152,7 +143,6 @@ std::string as_string(BinaryOctet *a) {
     return result;
 }
 
-
 // for std::cout
 std::ostream &operator<<(std::ostream &os, const BinaryOctet &toBePrinted) {
     os << as_string(toBePrinted);
@@ -163,7 +153,6 @@ std::ostream &operator<<(std::ostream &os, const BinaryOctet &toBePrinted) {
 std::ostream &operator<<(std::ostream &os, BinaryOctet *toBePrinted) {
     os << as_string(toBePrinted);
     return os;
-
 }
 
 
@@ -192,4 +181,4 @@ int main(int argc, char **argv) {
     std::cout << "==============   doCalculation   ================" << std::endl;
     std::cout << "result = " << doCalculation(a, b) << std::endl;
     return 0;
-}
+}
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7969eb2..bc68644 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,8 +15,8 @@ add_executable(01_ENV_Testat 01_ENV/Testat/main.c 01_ENV/Testat/func1.c)
 add_executable(02_MENT_MP 02_MENT/MP/main_02_MENT.cpp)
 add_executable(02_MENT_Testat 02_MENT/Testat/main_02_MENT.cpp)
 
-add_executable(03_FLOW_MP 03_FLOW_a/MP/main_mp2_FLOW_a.cpp helpers/AnsiConsole.cpp)
-add_executable(03_FLOW_Testat 03_FLOW_a/Testat/main_mp2_FLOW_a.cpp helpers/AnsiConsole.cpp)
+add_executable(03_FLOW_MP 03_FLOW/MP/main_mp2_FLOW_a.cpp helpers/AnsiConsole.cpp)
+add_executable(03_FLOW_Testat 03_FLOW/Testat/main_mp2_FLOW_a.cpp helpers/AnsiConsole.cpp)
 
 add_executable(04_UDEF_MP 04_UDEF/MP/main_04_UDEF_e.cpp)
 add_executable(04_UDEF_Testat 04_UDEF/Testat/Testat.cpp)