package main

import . "fmt"

func main() {
	var n,m,p,q int
	Scan(&n,&m,&p,&q)
	x:=m*12+q*m
	ans:=n/x*12
	n%=x
	for i:=1;i<=12;i++ {
		if n<=0 {
			break
		}
		ans++
		n-=m
		if p<=i&&i<p+q {
			n-=m
		}
	}
	Println(ans)
}