#!/bin/python3

import sys

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

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)