/in/foo.cc: In function 'void Add(std::vector<Poly>&, std::vector<Poly>&)':
/in/foo.cc:40:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<L2.size(); i++)
               ~^~~~~~~~~~
/in/foo.cc:38:6: warning: unused variable 'n1' [-Wunused-variable]
  int n1=L1.size();
      ^~
/in/foo.cc:39:6: warning: unused variable 'n2' [-Wunused-variable]
  int n2=L2.size();
      ^~
/in/foo.cc: In function 'void Output(std::vector<Poly>&)':
/in/foo.cc:46:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<L.size()&&L[i].coef!=0; i++)
               ~^~~~~~~~~