/in/foo.cc: In function 'int main()':
/in/foo.cc:15:20: warning: 'f' may be used uninitialized in this function [-Wmaybe-uninitialized]
     cout<<e<<" "<<f;
                    ^
/in/foo.cc:15:14: warning: 'e' may be used uninitialized in this function [-Wmaybe-uninitialized]
     cout<<e<<" "<<f;
              ^~~