/in/foo.cc: In function 'int main()':
/in/foo.cc:7:10: warning: unused variable 'c' [-Wunused-variable]
  int a,b,c,m,n;
          ^
/in/foo.cc:19:8: warning: 'n' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<n<<endl;
        ^
/in/foo.cc:18:8: warning: 'm' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<m<<endl;
        ^