foo.cc: In function 'int bfs_1(int, int)':
foo.cc:36:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=1;i<c.size();i++)
                      ~^~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:78:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=0;i<c.size();i++)
                      ~^~~~~~~~~
foo.cc:71:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%c",&c);
             ~~~~~^~~~~~~~~
foo.cc:72:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%c%d",&c,&y);
             ~~~~~^~~~~~~~~~~~~~

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。