#include <bits/stdc++.h>

using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << endl
#define rup(a,b) (a+b-1)/b

using namespace std;

int main(){
    cout << fixed << setprecision(15);
    
    ll N,S;
    cin>>N>>S;
    ll right = N;
    ll left = 0;
    while (right-left>1){
        ll mid = (right+left)/2;
        ll a = mid*(mid+1)/2;
        if (a>=S) right = mid;
        else left = mid;
    }
    ll a = (right+1)*right/2;
    if (a==S){
        print(right);
        rep(i,1,right+1){
            cout << i << " ";
        }
    }else{
        print(right-1);
        ll b = a - S;
        rep(i,1,right+1){
            if (i == b) continue;
            cout << i << " ";
        }
    }
    cout << endl;
    
    //system("pause");
    return 0;
}