/in/foo.cc: In function 'int main()':
/in/foo.cc:10:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1;i<=a.size();i++) cnt++;
                 ~^~~~~~~~~~
/in/foo.cc:11:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1;i<=b.size();i++) ccnt++;
                 ~^~~~~~~~~~