#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    ans = 0
    while s > 0:
        if s >= p:
            s -= p
            ans += 1
        else:
            s = 0
        p -= d
        if p < m:
            p = m
    return ans

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)