/in/foo.cc: In function 'int main()':
/in/foo.cc:20:10: warning: unused variable 'key2' [-Wunused-variable]
  int key,key2,biaoji,now2=-1;
          ^~~~
/in/foo.cc:23:16: warning: 'biaoji' may be used uninitialized in this function [-Wmaybe-uninitialized]
  key=abs(biaoji-31)-1;
          ~~~~~~^~~