#!/bin/python

import sys

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    num_games = 0
    have_money = True
    prize = p
    while have_money == True:
        if prize > m:
            prize = prize
        else:
            prize = m
        if prize > s:
            have_money = False
            break
        if s >= prize:
            num_games += 1
            s = s - prize
            prize = p - num_games * d

    return num_games

if __name__ == "__main__":
    p, d, m, s = raw_input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    answer = howManyGames(p, d, m, s)
    print answer