#!/bin/python

import sys


if __name__ == "__main__":
    p, d, m, s = raw_input().strip().split(' ')
    p, d, m, s = [int(p), int(d), int(m), int(s)]
    cnt=0
    while s-p>=0:
        #print s,p
        s -= p
        if p-d<=m:
            p=m
        if p-d>=m:
            p-=d
            #print"x"
        
        cnt+=1
        
    print cnt