#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    g = 0
    c = p
    while True:
        s = s - c
        if s < 0:
            break
        g = g + 1
        if c - d >= m: 
            c = c - d
        else: c = m
    return g

            
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)