n,s = map(int,input().split())

for i in range(1,n+1):
    tmp = i*(i+1)//2
    if tmp >= s:
        idx = i
        sa = tmp-s
        break
ans = []
for i in range(1,idx+1):
    if i != sa:
        ans.append(i)
print(len(ans))
print(*ans)