#!/bin/python3

import sys

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

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)