N,S = map(int,input().split())

import sys
if S <= N:
    print(1)
    print(S)
    exit()
M = N * (N + 1) // 2
if M - S <= N:
    ans = []
    for i in range(1,N + 1):
        if i != M - S:
            ans.append(i)
    print(len(ans))
    print(*ans)
    exit()
    
tmp = 0
ans = []
for i in range(N,0,-1):
    if tmp + i <= S:
        ans.append(i)
        tmp += i
    else:
        break
if S - tmp > 0:
    ans.append(S - tmp)
print(len(ans))
print(*ans[::-1])