/in/foo.cc: In function 'int main()':
/in/foo.cc:24:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(p1<a.size()&&p2<b.size())
           ~~^~~~~~~~~
/in/foo.cc:24:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(p1<a.size()&&p2<b.size())
                        ~~^~~~~~~~~
/in/foo.cc:30:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         else if(a[p1]==b[p2]&&p1<a.size())
                               ~~^~~~~~~~~
/in/foo.cc:40:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while(p1<a.size())
               ~~^~~~~~~~~
/in/foo.cc:42:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(p2<b.size())
           ~~^~~~~~~~~