/in/foo.cc: In function 'int main()':
/in/foo.cc:17:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(i+1<s.size())
      ~~~^~~~~~~~~
/in/foo.cc:27:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(j<s.size())
       ~^~~~~~~~~
/in/foo.cc:32:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(j+1<s.size())
      ~~~^~~~~~~~~
/in/foo.cc:19:3: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(b>=5) a++;
   ^~