package main

import (
	"fmt"
)

func main() {
	solve281()
}

func solve281() {
	var d, a, b, c int
	fmt.Scan(&d, &a, &b, &c)
	var cnt1, cnt2 int
	b1 := b
	if a == 0 || c == 0 {
		cnt1 = -1
	}else{
		for a <= b1 || c <= b1 {
			cnt1++
			b1 = max(0, b1-d)
			if b1 == 0 {
				break
			}
		}
	}
	
	if b==0{
		cnt2 = -1
	}else{
		a1 := a
		for a1 >= b {
			cnt2++
			a1 = max(0, a1-d)
			if a1 == 0 {
				break
			}
		}
		c1 := c
		for c1 >= b {
			cnt2++
			c1 = max(0, c1-d)
			if c1 == 0 {
				break
			}
		}
		if a1 == c1 {
			cnt2 = -1
		}
	}

	//fmt.Println(cnt1, cnt2)
	if cnt1 == -1 && cnt2 == -1 {
		fmt.Println("-1")
	} else if cnt1 == -1 {
		fmt.Println(cnt2)
	} else if cnt2 == -1 {
		fmt.Println(cnt1)
	} else {
		fmt.Println(min(cnt1, cnt2))
	}

}

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

func min(a, b int) int {
	if a > b {
		a = b
	}
	return a
}