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 currentMoney = s;
        int currentCost = p;
        int games = 0;
        
        while (currentCost <= currentMoney) {
            currentMoney -= currentCost;
            
            if (currentCost - d >= m) {
                currentCost -= d;
            } else {
                currentCost = m;
            }
            
            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();
    }
}