/in/foo.cc: In function 'int main()':
/in/foo.cc:38:12: warning: unused variable 'j' [-Wunused-variable]
  int n,m,i,j,x,y,sum;
            ^
/in/foo.cc:38:18: warning: variable 'sum' set but not used [-Wunused-but-set-variable]
  int n,m,i,j,x,y,sum;
                  ^~~