code: add differ

main.cpp

@@ -7,6 +7,8 @@ int main()
     cout << "Enter A and B: ";
     int a, b;
     cin >> a >> b;
-    cout << "a + b = " << a + b << "\n";
+    cout << "A + B = " << a + b << '\n'
+    << "A - B = " << a - b << '\n';
+
     return 0;
 }