foo.cc: In function ‘int main()’:
foo.cc:8:13: warning: unused variable ‘bu’ [-Wunused-variable]
    8 |         int bu;//不及格
      |             ^~
foo.cc:9:13: warning: unused variable ‘hx’ [-Wunused-variable]
    9 |         int hx=0;
      |             ^~
foo.cc:12:13: warning: unused variable ‘zf’ [-Wunused-variable]
   12 |         int zf[n];
      |             ^~