#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    result = 0
    if(p == s):
        return 1
    elif(p > s):
        return 0
    while s>0:
        s = s - p
        p = p - d
        if(p<=m):
            p = m
        if(s>=0):
            result = result + 1
    return result
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)