foo.cc: In function 'int main()':
foo.cc:10:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s1.size();i++){
              ~^~~~~~~~~~
foo.cc:33:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<s3.size();i++)
               ~^~~~~~~~~~

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。