/in/foo.cc: In function 'void solve()':
/in/foo.cc:9:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.size();i++){
              ~^~~~~~~~~
/in/foo.cc:16:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(s[j]!=' '&&j<s.size())t+=s[j++];
                    ~^~~~~~~~~