#!/bin/python

import sys

def howManyGames(p, d, m, s):
    res = 0
    i = p
    while s >= i:
        s -= i
        i = max(i-d,m)
        if s >= 0:
            res = res + 1
    return res

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