#!/bin/python

import sys

def howManyGames(p, d, m, s):
    c=0
    sum1=0
    while sum1<s:
        sum1=sum1+p
        if p>m and p-d>=m:
            p=p-d
        else:
            p=d
        c=c+1
    diff=s-sum1
    if diff==0:
        print c+1
    elif diff>0:
        print c
    
    # Return the number of games you can buy

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