diff --git a/04_UDEF/MP/main_04_UDEF_e.cpp b/04_UDEF/MP/main_04_UDEF_e.cpp
index f1b92c9..7820b24 100644
--- a/04_UDEF/MP/main_04_UDEF_e.cpp
+++ b/04_UDEF/MP/main_04_UDEF_e.cpp
@@ -5,15 +5,18 @@
 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
+    char bitsAsDigits[bitsPerOctet]{}; // bit values as chars
     BinaryOctet(int x = 0);
-
+    BinaryOctet& operator=(int const &a);
     BinaryOctet(const BinaryOctet &) = default;
+private:
+    BinaryOctet init(int x);
 };
 
-BinaryOctet::BinaryOctet(int x) {
-    int length = std::to_string(x).length() * 4;
+BinaryOctet BinaryOctet::init(int x) {
+    int length = static_cast<int>(std::to_string(x).length() * 4);
     while (x >= 1) {
         bitsAsDigits[length] = (x % 2 == 0) ? '1' : '0';
         x = x / 2;
@@ -25,24 +28,47 @@ BinaryOctet::BinaryOctet(int x) {
         if (c == '1') i++;
     }
     evenParity = i % 2 == 0;
+
+    return *this;
+}
+
+BinaryOctet::BinaryOctet(int x) {
+    init(x);
 }
 
 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 true;
 }
 
 BinaryOctet operator--(BinaryOctet &id, int) {
 
+    return id;
 }
 
 BinaryOctet operator+(BinaryOctet a, BinaryOctet b) {
+    BinaryOctet result;
 
+    for (int i = 0; i < bitsPerOctet; ++i) {
+        if(a.bitsAsDigits[i] == b.bitsAsDigits[i]) result.bitsAsDigits[i] = '0';
+        else result.bitsAsDigits[i] = '1';
+    }
+
+    return result;
 }
 
 BinaryOctet operator/(BinaryOctet a, BinaryOctet b) {
 
 }
 
+BinaryOctet& BinaryOctet::operator=(int const &i) {
+    init(i);
+    return *this;
+}
+
 BinaryOctet doCalculation(BinaryOctet a, BinaryOctet b) {
     BinaryOctet result;
 
@@ -65,16 +91,17 @@ std::string as_string(BinaryOctet a) {
 }
 
 // for std::cout
-/*std::ostream& operator<< (std::ostream& os, const BinaryOctet &toBePrinted){
-	os << "(" << ")";
+std::ostream& operator<< (std::ostream& os, const BinaryOctet &toBePrinted){
+	os << as_string(toBePrinted);
 	return os;
-}*/
+}
 
 int main(int argc, char **argv) {
     BinaryOctet a = 0b00001111;
     BinaryOctet b = 0b00000110;
-    println(new BinaryOctet(5));
-    println(new BinaryOctet(5));
+    std::cout << new BinaryOctet(5) << std::endl;
+    println(a + b);
+    std::cout << a + b << std::endl;
     //println("result = ", doCalculation(a,b));
     //std::cout << "result = " << doCalculation(a,b) << std::endl;
     return 0;
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 08239cd..fd3be0c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,8 +17,7 @@ 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(04_UDEF_MP_1 04_UDEF/MP/main_04_UDEF_e.cpp)
-add_executable(04_UDEF_MP_2 04_UDEF/MP/main_04_UDEF_a.cpp)
+add_executable(04_UDEF_MP 04_UDEF/MP/main_04_UDEF_e.cpp)
 add_executable(04_UDEF_Testat 04_UDEF/Testat/Testat.cpp)
 
 add_executable(05_OO_MP 05_OO/MP/shapes_main.cpp helpers/AnsiConsole.cpp)