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 games=0,j=0;
        for (int i=p;i>=m;i=i-d)
        {
            j=j+i;
            if (j<s)
                games++;
        }
        int k=j+m;
        if(k<s)
        {
            for (int l=k;l<=s;l=l+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();
    }
}