#!/bin/python3

import sys

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

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)