import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    private static int countGames = 0;
    static int howManyGames(int p, int d, int m, int s) {
        if(s < p) return countGames;
        s -= p;
        p = (p-d<m)?m:p-d;
        countGames++;
        return howManyGames(p,d,m, s);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int p = in.nextInt();
        int d = in.nextInt();
        int m = in.nextInt();
        int s = in.nextInt();
        int answer = howManyGames(p, d, m, s);
        System.out.println(answer);
        in.close();
    }
}