/in/foo.cc: In function 'int main()':
/in/foo.cc:4:9: error: 'cin' was not declared in this scope
    4 |         cin>>a>>b;
      |         ^~~
/in/foo.cc:23:9: error: 'cout' was not declared in this scope
   23 |         cout<<a1<<" "<<c<<endl;
      |         ^~~~
/in/foo.cc:23:27: error: 'endl' was not declared in this scope
   23 |         cout<<a1<<" "<<c<<endl;
      |                           ^~~~