#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    total = 0
    many = 0
    now = p
    total = total + now
    if total <= s:
        many = 1
    else:
        return 0
    if now -d > m:
        now = now - d
    else:
        now = m
    while total+now <= s :
        total = total + now
        many = many+1
        if now-d > m:
            now = now -d
        else:
            now = m
    return many
    # 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)