#!/bin/python3

import sys

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

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)