import java.util.Scanner;

public class Solution {

    static int howManyGames(int p, int d, int m, int s) {

        int sum = 0, discount_count = 0, games = 0;
        while (sum + m <= s) {
            int total_discount = (discount_count++ * d);
            int cost = p - total_discount;
            sum += cost < m ? m : cost;
            if (sum <= s)
                games++;
        }
        return games;
    }

    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();
    }
}