#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    if s<p:
        return 0
    if s == p:
        return 1
    if p==m:
        return s//m
    else:
        return 1 + (howManyGames(max(p-d,m),d,m,s-p))
        

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)