using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
class Solution {

    static int howManyGames(int p, int d, int m, int s) {
        int sum = 0;
        int sale = 0;
        if (s < p)
        {
            return 0;
        }
        while (s - Math.Max(p - sale * d, m) >= 0)
        {
            sum++;
            s = s - Math.Max(p - sale * d, m);
            sale++;
            Console.Error.WriteLine(s);
        }
        return sum;
    }

    static void Main(String[] args) {
        string[] tokens_p = Console.ReadLine().Split(' ');
        int p = Convert.ToInt32(tokens_p[0]);
        int d = Convert.ToInt32(tokens_p[1]);
        int m = Convert.ToInt32(tokens_p[2]);
        int s = Convert.ToInt32(tokens_p[3]);
        int answer = howManyGames(p, d, m, s);
        Console.WriteLine(answer);
    }
}