Wrong Answer
/in/foo.cc: In function 'int main()':
/in/foo.cc:54:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0; i < Md.size(); i++) {
~~^~~~~~~~~~~
/in/foo.cc:65:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0; i < Nd.size(); i++) {
~~^~~~~~~~~~~
