#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int N,S;
  cin>>N>>S;
  vector<int> A={};
  for(int i=N;i>=1;i--){
      if(S >= i){
          A.push_back(i); 
          S -= i;
      } 
  }
  cout<<A.size()<<endl;
  reverse(A.begin(),A.end());
  for(int i=0;i<A.size();i++) cout<<A[i]<<' ';
  cout<<endl;
}