/in/foo.cc: In function 'bool check(int, int)':
/in/foo.cc:10:18: 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:49:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<sen.size();i++)
                 ~^~~~~~~~~~~
/in/foo.cc:70:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<sen.size();i++)
                 ~^~~~~~~~~~~