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

public class Solution {

    static int howManyGames(int p, int d, int m, int s) {
        int numberOfGames = 0;

        if (s > p) {
            int moneyLeft = s;
            int priceOfGame = p;
            while (moneyLeft >= priceOfGame) {
                numberOfGames++;
                moneyLeft = moneyLeft - priceOfGame;
                if (priceOfGame - d < m) {
                    priceOfGame = m;
                } else {
                    priceOfGame = priceOfGame - d;
                }
            }
        }
        return numberOfGames;
    }

    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();
    }
}