#!/bin/python3

import sys

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

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)