#!/bin/python

import sys

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

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