#!/bin/python3

import sys

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

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)