package main

import . "fmt"

func main() {
	var n, s int64
	Scan(&n,&s)
	a := []int64{}
	for n > 0 && s > 0 {
		if n > s {
			n = s
		}
		a = append(a, n)
		s -= n
		n--
	}
	if s > 0 {
		Println(-1)
		return
	}
	Println(len(a))
	for i, v := range a {
		if i > 0 {
			Print(" ")
		}
		Print(v)
	}
	Println()
}