#!/bin/python3

import sys

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