View Compilation Error

2_28141_2117386_9515.cpp: In function 'int main()':
2_28141_2117386_9515.cpp:5:9: error: 'cin' was not declared in this scope
  while (cin >> n >> m)
         ^
2_28141_2117386_9515.cpp:11:3: error: 'cout' was not declared in this scope
   cout << sum << endl;
   ^
2_28141_2117386_9515.cpp:11:18: error: 'endl' was not declared in this scope
   cout << sum << endl;
                  ^