foo.cc: In function 'int main()':
foo.cc:48:7: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  fgets(str, 100000, stdin);
  ~~~~~^~~~~~~~~~~~~~~~~~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。