package main

import "fmt"

func main() {
	var a, b, c, d int
	fmt.Scan(&a, &b, &c, &d)

	ans := 0
	for {
		if a-1 < 0 || b-c < 0 || d-c-1 < 0 {
			break
		}
		a--
		b -= c
		d -= c + 1
		ans++
	}
	fmt.Println(ans)
}