# -*- coding=utf-8 -*-
#【考察】お尻から見ていけばいけそう
from collections import deque

if __name__ == "__main__":
    N, S = list(map(int, input().split(" ")))
    A = [n for n in range(1, N + 1)]
    A.sort(reverse=True)

    answer = deque([])    
    summary = 0
    for a in A:
        if summary + a <= S:
            answer.appendleft(a)
            summary += a
    
    print(len(answer))
    print(*answer)