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

A=[0]*(N+1)
for i in range(N,0,-1):
    if S>=i:
        A[i]=1
        S-=i
    elif S>0:
        A[S]=1
        break

print(sum(A))
print(*[i for i in range(1,N+1) if A[i]])