foo.cc: In function 'int main()':
foo.cc:21:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0; j<=str.length()-1; j++) {
                ~^~~~~~~~~~~~~~~~
foo.cc:17:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~

自豪的采用 HydroJudger 进行评测(github.com/hydro-dev/HydroJudger)

{"receive":"2020-06-29T13:25:15.370Z","handle":"2020-06-29T13:25:15.370Z","cache_start":"2020-06-29T13:25:15.376Z","read_cases":"2020-06-29T13:25:15.491Z","judge":"2020-06-29T13:25:15.498Z","done":"2020-06-29T13:25:16.435Z"}