foo.cc: In function 'int main()':
foo.cc:56:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < a.size(); i++)
                  ~~^~~~~~~~~~
foo.cc:58:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < a.size(); i++)
                  ~~^~~~~~~~~~

自豪的采用jd5进行评测(github.com/masnn/jd5)

{"receive":"2020-02-23T07:31:47.092Z","handle":"2020-02-23T07:31:47.092Z","cache_start":"2020-02-23T07:31:47.093Z","read_cases":"2020-02-23T07:31:47.262Z","judge":"2020-02-23T07:31:47.263Z","done":"2020-02-23T07:31:48.074Z"}