#!/bin/python3

import sys

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