#!/bin/python3

import sys

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