/in/foo.cc: In function 'int main()':
/in/foo.cc:83:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1;i<=Index.size();i++)
                 ~^~~~~~~~~~~~~~
/in/foo.cc:88:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int k=0;k<Index[i-1].size();k++)//用每一个可能的选项更新dp vector从0开始
                         ~^~~~~~~~~~~~~~~~~~