#!/bin/python3

import sys

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

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)