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 r=p;int next_price=p;int c=0;
        for(int i=r;i<=s;i=i+next_price)
        {
            if(next_price <= m && i<=s)
            {
                c++;
                next_price = next_price-0;
            }
            else if(next_price >m && i<=s)
            {
                c++;
                next_price = next_price-d;
            }
            else
                break;
        }
        return c-1;
    }

    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();
    }
}