import java.util.Scanner;

public class Solution {
    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 k = 0;
        int quantity = 0;
        while (true) {
            int price = p - k * d;
            if (price < m) {
                price = m;
            }
            s -= price;
            if (s >= 0) {
                quantity++;
            } else {
                break;
            }
            k++;
        }
        System.out.println(quantity);
    }
}