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) {
        // Return the number of games you can buy
        if (s < p) {
            return 0;
        }
        int newPrice = p;
        int remainingWallet = s;
        
        if (newPrice - d <= m) {
            newPrice = m;
        } else {
            newPrice = newPrice - d;
        }
        remainingWallet -= p;
        return 1 + howManyGames(newPrice, d, m, remainingWallet);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int p = in.nextInt();           // price for games
        int d = in.nextInt();           // reduction in price
        int m = in.nextInt();           // minimum price
        int s = in.nextInt();           // dollar amount in wallet
        int answer = howManyGames(p, d, m, s);
        System.out.println(answer);
        in.close();
    }
}