#!/bin/python

import sys

def howManyGames(p, d, m, s):
    count=0
    while(s>0):
        s-=p
        if (p-d)>m: p-=d
        else : p=m
        count+=1
    if s<0: count-=1
    return count

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