/in/foo.cc: In function 'int main()':
/in/foo.cc:6:9: error: 'cin' was not declared in this scope
    6 |         cin <<a<<b;
      |         ^~~
/in/foo.cc:7:9: error: 'cout' was not declared in this scope
    7 |         cout>>a+b>>endl;
      |         ^~~~
/in/foo.cc:7:20: error: 'endl' was not declared in this scope
    7 |         cout>>a+b>>endl;
      |                    ^~~~