def howManyGames(p, d, m, s):
    games = 0
    while s - p >= 0:
        games += 1
        s -= p
        if p - d >= m:
            p -= d
        else: p = m
    return games

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