#!/bin/python

import sys

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

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