/in/foo.cc: In function 'int main()':
/in/foo.cc:9:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<a.size();)
                 ~^~~~~~~~~
/in/foo.cc:11:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(j=i;j<i+b.size()&&j<a.size();j++)
                 ~^~~~~~~~~~~
/in/foo.cc:11:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(j=i;j<i+b.size()&&j<a.size();j++)
                               ~^~~~~~~~~
/in/foo.cc:19:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(j==i+b.size()-1)
            ~^~~~~~~~~~~~~~