#!/bin/python3

import sys
import math

def howManyGames(p, d, m, s):
    n=math.floor((p-m)/d+1)
    #sum1=math.floor((n*(2*p-(n-1)*d))/2)
    #sum1+=d*(s-n)
    sum1=0
    c=0
    for i in range(0,n):
        sum1+=p
        p-=d
        c+=1
        #print(sum1,c)
        if(sum1>s):
            return c-1
    for i in range(n,s):
        sum1+=m
        c+=1
        if(sum1>s):
            return c-1
    return c

if __name__ == "__main__":
    p, d, m, s = input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    answer = howManyGames(p, d, m, s)
    print(answer)