#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    c = 0
    while p > m and s >= p:
        c += 1
        s -= p
        p = max(p - d, m)
    return c + 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)