#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second

const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll INF = 1LL << 60;
const ll N_MAX = 2e5;

int main(){
    ll n, s;
    cin >> n >> s;

    vector<bool> check(n+1, false);
    ll sum = 0;
    for(ll i=1; i<=n; i++){
        if(sum+i < s){
            sum += i;
            check[i] = true;
        }else{
            check[i] = true;
            check[sum+i - s] = false;
            break;
        }
    }

    ll k = 0;
    for(ll i=1; i<=n; i++) k += check[i];
    cout << k << endl;
    for(ll i=1; i<=n; i++) if(check[i]) cout << i << " ";
    cout << endl;
}