diff --git a/Lesson_1/Task_1/main.cpp b/Lesson_1/Task_1/main.cpp
index b851994..efa4f74 100644
--- a/Lesson_1/Task_1/main.cpp
+++ b/Lesson_1/Task_1/main.cpp
@@ -1,7 +1,10 @@
 #include <iostream>
 
+using namespace std;
+
 int main()
 {
-    std::cout << "Stanislav" << std::endl << "Mykhailenko" << std::endl;
+    cout << "Stanislav" << endl;
+    cout << "Mykhailenko" << endl;
     return 0;
 }
diff --git a/Lesson_1/Task_2/main.cpp b/Lesson_1/Task_2/main.cpp
index 7b353ca..402abcd 100644
--- a/Lesson_1/Task_2/main.cpp
+++ b/Lesson_1/Task_2/main.cpp
@@ -1,17 +1,19 @@
 #include <iostream>
 
+using namespace std;
+
 int main()
 {
     float firstNumber = 0;
     float secondNumber = 0;
 
-    std::cout << "Enter the first number: ";
-    std::cin >> firstNumber;
+    cout << "Enter the first number: ";
+    cin >> firstNumber;
 
-    std::cout << "Enter the second number: ";
-    std::cin >> secondNumber;
+    cout << "Enter the second number: ";
+    cin >> secondNumber;
 
-    std::cout << firstNumber + secondNumber << std::endl;
+    cout << firstNumber + secondNumber << endl;
 
     return 0;
 }
diff --git a/Lesson_1/Task_3/main.cpp b/Lesson_1/Task_3/main.cpp
index 1ee6afb..30dbb95 100644
--- a/Lesson_1/Task_3/main.cpp
+++ b/Lesson_1/Task_3/main.cpp
@@ -1,21 +1,23 @@
 #include <iostream>
 
+using namespace std;
+
 int main()
 {
     int money = 0;
-    std::cout << "How much money do you earn? ";
-    std::cin >> money;
+    cout << "How much money do you earn? ";
+    cin >> money;
 
     if (money < 1000)
-        std::cout << "Work more. ";
+        cout << "Work more. ";
     if (money > 1000) {
         if (money > 1000000)
-            std::cout << "You are a millionaire. ";
+            cout << "You are a millionaire. ";
         if (money < 1000000)
-            std::cout << "You work great. ";
+            cout << "You work great. ";
     }
 
-    std::cout << "You are doing great!" << std::endl;
+    cout << "You are doing great!" << endl;
 
     return 0;
 }
diff --git a/Lesson_1/Task_4/main.cpp b/Lesson_1/Task_4/main.cpp
index 6da8c35..09c05a5 100644
--- a/Lesson_1/Task_4/main.cpp
+++ b/Lesson_1/Task_4/main.cpp
@@ -1,20 +1,22 @@
 #include <iostream>
 
+using namespace std;
+
 int main()
 {
     float firstNumber = 0;
     float secondNumber = 0;
     float result = 0;
-    char operation;
+    char operation = 0;
 
-    std::cout << "Enter the first number: ";
-    std::cin >> firstNumber;
+    cout << "Enter the first number: ";
+    cin >> firstNumber;
 
-    std::cout << "Enter the second number: ";
-    std::cin >> secondNumber;
+    cout << "Enter the second number: ";
+    cin >> secondNumber;
 
-    std::cout << "Enter operation: ";
-    std::cin >> operation;
+    cout << "Enter operation: ";
+    cin >> operation;
 
     switch (operation) {
         case '+':
@@ -28,18 +30,18 @@ int main()
             break;
         case '/':
             if (secondNumber == 0) {
-                std::cout << "Division by zero" << std::endl;
+                cout << "Division by zero" << endl;
                 return 1;
             }
             result = firstNumber / secondNumber;
             break;
         default:
-            std::cout << "Unknown operation." << std::endl;
+            cout << "Unknown operation." << endl;
             return 2;
             break;
     }
 
-    std::cout << result << std::endl;
+    cout << result << endl;
 
     return 0;
 }
diff --git a/Lesson_1/Task_5/main.cpp b/Lesson_1/Task_5/main.cpp
index 56e981f..b90df32 100644
--- a/Lesson_1/Task_5/main.cpp
+++ b/Lesson_1/Task_5/main.cpp
@@ -2,6 +2,8 @@
 #include <complex>
 #include <iostream>
 
+using namespace std;
+
 int main()
 {
     float a = 0;
@@ -9,24 +11,24 @@ int main()
     float c = 0;
     float D = 0;
 
-    std::cout << "Enter a: ";
-    std::cin >> a;
+    cout << "Enter a: ";
+    cin >> a;
 
-    std::cout << "Enter b: ";
-    std::cin >> b;
+    cout << "Enter b: ";
+    cin >> b;
 
-    std::cout << "Enter c: ";
-    std::cin >> c;
+    cout << "Enter c: ";
+    cin >> c;
 
     D = pow(b, 2) - 4 * a * c;
 
-    std::complex<float> root = std::sqrt(std::complex<float>(D));
+    complex<float> root = sqrt(complex<float>(D));
 
-    std::complex<float> x1 = (-b + root) / (2 * a);
-    std::complex<float> x2 = (-b - root) / (2 * a);
+    complex<float> x1 = (-b + root) / (2 * a);
+    complex<float> x2 = (-b - root) / (2 * a);
 
-    std::cout << "x1 = " << x1 << std::endl;
-    std::cout << "x2 = " << x2 << std::endl;
+    cout << "x1 = " << x1 << endl;
+    cout << "x2 = " << x2 << endl;
 
     return 0;
 }
diff --git a/Lesson_1/Task_6/main.cpp b/Lesson_1/Task_6/main.cpp
index c8c30c1..53313c4 100644
--- a/Lesson_1/Task_6/main.cpp
+++ b/Lesson_1/Task_6/main.cpp
@@ -1,25 +1,27 @@
 #include <iostream>
 
+using namespace std;
+
 int main()
 {
     int size = 0;
 
-    std::cout << "Enter size: ";
-    std::cin >> size;
+    cout << "Enter size: ";
+    cin >> size;
 
     for (int iteration = 0; iteration < size; ++iteration) {
         int spaces = size - iteration - 1;
         int asterisks = 1 + iteration * 2;
         for (int space = 0; space < spaces; ++space)
-            std::cout << " ";
+            cout << " ";
         for (int asterisk = 0; asterisk < asterisks; ++asterisk)
-            std::cout << "*";
-        std::cout << std::endl;
+            cout << "*";
+        cout << endl;
     }
 
     for (int space = 0; space < size - 1; ++space)
-        std::cout << " ";
-    std::cout << "*" << std::endl;
+        cout << " ";
+    cout << "*" << endl;
 
     return 0;
 }
diff --git a/Lesson_1/Task_7/main.cpp b/Lesson_1/Task_7/main.cpp
index 6a4ec3a..65b7db3 100644
--- a/Lesson_1/Task_7/main.cpp
+++ b/Lesson_1/Task_7/main.cpp
@@ -1,6 +1,8 @@
 #include <cmath>
 #include <iostream>
 
+using namespace std;
+
 int main()
 {
     float x = 0;
@@ -8,23 +10,21 @@ int main()
     float N = 0;
     float distance = 0;
 
-    std::cout << "x = ";
-    std::cin >> x;
+    cout << "Enter your x: ";
+    cin >> x;
 
-    std::cout << "y = ";
-    std::cin >> y;
+    cout << "Enter your y: ";
+    cin >> y;
 
-    std::cout << "N = ";
-    std::cin >> N;
-
-    if (x > N || y > N) {
-        std::cout << "Beyond radius." << std::endl;
-        return 1;
-    }
+    cout << "Enter radius N: ";
+    cin >> N;
 
     distance = sqrt(pow(x, 2) + pow(y, 2));
 
-    std::cout << distance << std::endl;
+    cout << distance << " from the center";
+    if (distance > N)
+    	cout << " (beyond radius)";
+    cout << endl;
 
     return 0;
 }