/in/foo.cc: In function 'int main()':
/in/foo.cc:18:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < n.size(); i++)
                    ^
/in/foo.cc:21:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < buff.size(); j++)
                     ^
/in/foo.cc:26:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < n[i] - k[i]; j++)  //去掉几个人
                     ^
/in/foo.cc:37:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < buff.size(); j++)
                     ^