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
import random
n, s = mi()

class ListDict(object):
    def __init__(self):
        self.item_to_position = {}
        self.items = []

    def add_item(self, item):
        if item in self.item_to_position:
            return
        self.items.append(item)
        self.item_to_position[item] = len(self.items)-1

    def remove_item(self, item):
        position = self.item_to_position.pop(item)
        last_item = self.items.pop()
        if position != len(self.items):
            self.items[position] = last_item
            self.item_to_position[last_item] = position

    def choose_random_item(self):
        return random.choice(self.items)

summ = 0
ans = []
D = ListDict()

for i in range(1, n + 1):
    D.add_item(i)
cnt = 0
while True:
    cnt += 1
    now = D.choose_random_item()
    if summ + now <= s:
        summ += now
        ans.append(now)
        D.remove_item(now)
        if summ == s:
            break
    if cnt >= 10 ** 5 and summ != s:
        cnt = 0
        ans = []
        summ = 0
        D = ListDict()

        for i in range(1, n + 1):
            D.add_item(i)


print(len(ans))
print(*sorted(ans))