N, S = map(int, input().split())
for i in range(1, N + 1):
    if S <= i * (i + 1)//2:
        v = i * (i + 1)//2 - S
        ans = []
        for j in range(1, i + 1):
            if j != v:
                ans.append(j)
        print(len(ans))
        print(*ans)
        exit()