foo.cc: In function 'int main()':
foo.cc:21:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < s.length(); i++)
                   ~~^~~~~~~~~~~~
foo.cc:31:26: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
      if (first % 10 == 1 && second % 10 == 3 || first % 10 == 3 && second % 10 == 1)
          ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:40:27: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
       if (first / 10 == 1 && second / 10 == 3 || first / 10 == 3 && second / 10 == 1)
           ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~

自豪的采用jd5进行评测(github.com/masnn/jd5)

{"receive":"2020-02-24T07:00:44.785Z","handle":"2020-02-24T07:00:44.785Z","cache_start":"2020-02-24T07:00:44.785Z","read_cases":"2020-02-24T07:00:45.582Z","judge":"2020-02-24T07:00:45.582Z","done":"2020-02-24T07:00:46.289Z"}