View Compilation Error

0_0_20517540_13279.cpp: In function 'int main()':
0_0_20517540_13279.cpp:4:8: error: 'cin' was not declared in this scope
  while(cin >> a >> b)
        ^
0_0_20517540_13279.cpp:5:2: error: 'cout' was not declared in this scope
  cout << a + b << endl;
  ^
0_0_20517540_13279.cpp:5:19: error: 'endl' was not declared in this scope
  cout << a + b << endl;
                   ^