#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
#define REP(i,n) for(ll i=0;i<(n);i++)
#define ALL(v) v.begin(),v.end()
template<typename T> bool chmax(T &x, const T &y) {return (x<y)?(x=y,true):false;};
template<typename T> bool chmin(T &x, const T &y) {return (x>y)?(x=y,true):false;};
constexpr ll MOD=998244353;
constexpr ll INF=2e18;

int main(){
    ll n, s; cin >> n >> s;
    VI a;
    for(int i=n;i>=1;i--){
        if(i<=s){
            s-=i;
            a.push_back(i);
        }
    }
    reverse(ALL(a));
    int m=a.size();
    cout << m << endl;
    REP(i,m) cout << a[i] << " \n"[i==m-1];
    return 0;
}