#!/bin/python

import sys

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    buy = 0
    money = s
    price = p
    if not s:
        return 0
    while money > 0:
        if not buy:
            price = p
        elif price - d > m:
            price -= d
        else:
            price = m

        money -= price

        if money >= 0:
            buy += 1
    return buy

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