/in/foo.cc: In function 'int main()':
/in/foo.cc:7:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<a.size()-1;i++) cout<<a[i];
              ~^~~~~~~~~~~
/in/foo.cc:8:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<b.size();i++) cout<<b[i];
              ~^~~~~~~~~