#!/bin/python

import sys

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