#!/bin/python3

import sys

def howManyGames(p, d, m, s):
    count=0
    pur=0
    while(pur<=s):
        #print("p=",p," p=",pur)
        pur=pur+p
        if p-d>=m:
            p=p-d
        else:
            p=m
        count=count+1
    return count-1
        

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)