/in/foo.cc: In function 'int main()':
/in/foo.cc:36:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(b.size()>=mm)
       ~~~~~~~~^~~~
/in/foo.cc:48:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int k=0;k<b.size();k++)
                 ~^~~~~~~~~