foo.cc: In function 'int main()':
foo.cc:5:9: warning: 'tt' may be used uninitialized in this function [-Wmaybe-uninitialized]
  char a,tt;
         ^~

正在同步测试数据，请稍后
自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。