#!/bin/python

import sys

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

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