/in/foo.cc: In function 'void Mulh(std::vector<int>&, std::vector<int>&)':
/in/foo.cc:58:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(j=0;j<numx2.size()-1-i;j++)
           ~^~~~~~~~~~~~~~~~~
/in/foo.cc:50:8: warning: unused variable 'k' [-Wunused-variable]
  int i,k,j;
        ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:85:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<numx1.size();i++)
          ~^~~~~~~~~~~~~