foo.cc: In function 'int main()':
foo.cc:6:2: error: 'cin' was not declared in this scope
  cin >> a >> b;
  ^~~
foo.cc:6:2: note: suggested alternative: 'main'
  cin >> a >> b;
  ^~~
  main
foo.cc:7:2: error: 'cout' was not declared in this scope
  cout << a + b << endl;
  ^~~~
foo.cc:7:19: error: 'endl' was not declared in this scope
  cout << a + b << endl;
                   ^~~~
foo.cc:7:19: note: suggested alternative: 'enum'
  cout << a + b << endl;
                   ^~~~
                   enum

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