#!/bin/python3

import sys

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

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)