#!/bin/python

import sys

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

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