/in/foo.cc: In function 'bool check(int, int)':
/in/foo.cc:11:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<sen[p].size();i++)
              ~^~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:52:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<sen.size();i++)
              ~^~~~~~~~~~~
/in/foo.cc:73:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<sen.size();i++)
              ~^~~~~~~~~~~