/in/foo.cc: In function 'long long int cal(std::vector<long long int>&)':
/in/foo.cc:13:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(i!=a.size()/i)d.push_back(a.size()/i);
       ~^~~~~~~~~~~~
/in/foo.cc:17:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<d.size();i++){
              ~^~~~~~~~~
/in/foo.cc:20:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int k=j;k<a.size();k+=d[i]){
                ~^~~~~~~~~