/in/foo.cc: In function 'int main()':
/in/foo.cc:5:14: warning: unused variable 'z' [-Wunused-variable]
  int n,i,j,s,z,y;
              ^
/in/foo.cc:5:16: warning: unused variable 'y' [-Wunused-variable]
  int n,i,j,s,z,y;
                ^
/in/foo.cc:30:8: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
     s++;
        ^