/in/foo.cc: In function 'int main()':
/in/foo.cc:5:2: error: 'cin' was not declared in this scope
  cin>>a>>b;
  ^~~
/in/foo.cc:21:10: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
    if(l=5)
          ^
/in/foo.cc:29:2: error: 'cout' was not declared in this scope
  cout<<z<<endl<<o;
  ^~~~
/in/foo.cc:29:11: error: 'endl' was not declared in this scope
  cout<<z<<endl<<o;
           ^~~~