#!/bin/python3

import sys

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

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)