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 i,  k=0, x=0, count=1;
        int arr[] = new int[p/d];
        for(i=p; i>=m; i=i-d)
        {
            arr[k++] = i;
        }
        k=0;
        while(x<=s&&k<p/d)
        {
            x+=arr[k++];
            count++;
        }
        if((x-s)>0)
            while(x<=s)
            {
                x+=arr[k-1];
                count++;
            }
        return count;
    }

    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();
    }
}