foo.cc: In function 'int hui(int)':
foo.cc:18:10: warning: unused variable 'y' [-Wunused-variable]
  int cnt,y;
          ^
foo.cc: In function 'int main()':
foo.cc:8:13: warning: 'x' is used uninitialized in this function [-Wuninitialized]
  cout<<hui(x)<<endl;
             ^
foo.cc: In function 'int hui(int)':
foo.cc:32:9: warning: 'cnt' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return cnt;
         ^~~