#!/bin/python

import sys

def equation(p, d, m, s):
    i = 0
    while True:
        s = s - max(p - i *d, m)
        yield s
        i += 1

def howManyGames(p, d, m, s):
    # Return the number of games you can buy
    for i, remainder in enumerate(equation(p, d, m, s)):
        #print i, remainder
        if remainder < 0:
            return i

if __name__ == "__main__":
    p, d, m, s = raw_input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    answer = howManyGames(p, d, m, s)
    print answer