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
        int money = s;
        int numGames = 0;
        while (money > 0)
        {
            if (money - p >= 0)
            {
                if ( p < m)
                {
                    p = m;
                }
                money = money - p;
                numGames++;
                p = p - d;
                if (p < m )
                {
                    p = m;
                }
            }
            else{
                money = -1;
            }
            
        }
        return numGames;
    }

    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();
    }
}