/in/foo.cc: In function 'int main()':
/in/foo.cc:8:10: warning: unused variable 'm' [-Wunused-variable]
    int n,m,sum;
          ^
/in/foo.cc:15:15: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
    cout << sum;
               ^