/in/foo.cc: In function 'int main()':
/in/foo.cc:6:5: error: 'cin' was not declared in this scope
    6 |     cin >> a >> b;
      |     ^~~
/in/foo.cc:7:5: error: 'cout' was not declared in this scope
    7 |     cout << a + b << endl;
      |     ^~~~
/in/foo.cc:7:22: error: 'endl' was not declared in this scope
    7 |     cout << a + b << endl;
      |                      ^~~~