/in/foo.cc: In function 'int main()':
/in/foo.cc:35:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<A[x].size();i++){
               ~^~~~~~~~~~~~
/in/foo.cc:53:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<A[x].size();i++){
               ~^~~~~~~~~~~~