#!/bin/python

import sys

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