package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
	"sort"
)

func getCount(d, h, h1, h2, h3, c int) int {
	for {
		var t = h - c * d
		var mx = max(0, t)
		if h1 == mx || h2 == mx || h3 == mx {
			c+=1
		}else {
			break
		}
		if t < 0 {
			c = -1
			break
		}
	}
	return c
}
func choiceMinNonNeg(V ...int) int {
	v := []int(V)
	sort.Ints(v)
	for _, k := range v {
		if k < 0 {
			continue
		}
		return k
	}
	return -1
}

func solve() int {
	var d = nextInt()
	var h1 = nextInt()
	var h2 = nextInt()
	var h3 = nextInt()



	if h1 != h3 && (h1-h2)*(h2-h3) < 0 {
		// そのまま門松になっている
		if h1 != h3 {
			return 0
		}
		if h1-d == h2 {
			return -1
		}else {
			return 1

		}
	}
	if d == 0 {
		return -1
	}
	if h1 == h3 {
		if h1 == h2 {
			if h1 >= 2*d {
				return 3
			}
			if h1 > d {
				return 1
			}
			return -1
		}
		if h1 < d {
			return -1
		}
		if h2 > h1 {
			return 1
		}
		if h1-d == h2 {
			if h2 >= d {
				return 3
			}else {
				return -1
			}
		}
	}

	// 単調減少か単調増加になっている

	var A = abs(h2 - h1) / d + 1
	var B = abs(h3 - h2) / d + 1

	if h1 < h3 {
		// h2を短くするかh3を短くする

		A = getCount(d, h2, h1, h2, h3, A)
		B = getCount(d, h3, h1, h2, h3, B)

		return choiceMinNonNeg(A, B)
	}else if h1 > h3 {
		// h2を短くするかh3を短くする
		A = getCount(d, h1, h1, h2, h3, A)
		B = getCount(d, h2, h1, h2, h3, B)

		return choiceMinNonNeg(A, B)
	}
	return -1
}

func main() {
	fmt.Println(solve())

}

var s = bufio.NewScanner(os.Stdin)

func next() string {
	s.Split(bufio.ScanWords)
	s.Scan()
	return s.Text()
}

func nextLine() string {
	s.Split(bufio.ScanLines)
	s.Scan()
	return s.Text()
}

func nextInt() int {
	i, e := strconv.Atoi(next())
	if e != nil {
		panic(e)
	}
	return i
}
func nextLong() int64 {
	i, e := strconv.ParseInt(next(), 10, 64)
	if e != nil {
		panic(e)
	}
	return i
}
func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

func minA(arg ...int) int {
	var s = arg[0]
	for _, v := range arg {
		s = min(s, v)
	}
	return s
}

func min(a int, b int) int {
	if a < b {
		return a
	}
	return b
}
func max(a int, b int) int {
	if a < b {
		return b
	}
	return a
}