#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    i = 0
    total = 0
    while total <= s:
        term = p - i * d
        if term < m:
            term = m
        total += term
        i += 1
    return i - 1

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)