/in/foo.cc: In function 'void init2(int)':
/in/foo.cc:28:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<prime_factor[i].size();++j){
                     ~^~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:63:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<factor_zhishu[i].size();++j){
                     ~^~~~~~~~~~~~~~~~~~~~~~~~