#!/bin/python3

import sys

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