#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    if p > s:
        return 0
    elif p == s:
        return 1
    else:
        for i in range(100000):
            if p-(d*i) < m:
                pr=m
            else:
                pr=p-(d*i)
            s-=pr
            if s < 0:
                return i
            elif s == 0:
                return i+1
    

if __name__ == "__main__":
    p, d, m, s = list(map(int, input().strip().split(' ')))
    answer = howManyGames(p, d, m, s)
    print(answer)