import sys
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
INF = 2 ** 63 - 1
mod = 998244353

n, s = mi()
ans = []
summ = 0
for i in range(n, 0, -1):
    if summ + i <= s:
        ans.append(i)
        summ += i
print(len(ans))

print(*ans)