#include <bits/extc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define all(x) (x).begin(),(x).end()

using std::cin;
using std::cout;
using std::vector;
using std::string;
using std::istream;
using std::ostream;
using ll = long long;

int main() {
    int n; ll s;
    cin >> n >> s;
    
    vector<int> a;
    for (int i = n; i >= 1; --i) {
        if (s >= i) {
            s -= i;
            a.push_back(i);
        }
    }
    reverse(all(a));
    cout << a.size() << '\n';
    for (int x : a) cout << x << ' ';
    
    return 0;
}