import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
		Scanner in = new Scanner(System.in);

		int p = in.nextInt(), d = in.nextInt(), m = in.nextInt(), s = in.nextInt();

		int count = 0;
		while (s > 0) {
			if (s - p >= 0) {
				s -= p;
			} else {
				break;
			}
			if (p - d >= m) {
				p -= d;
			} else {
                p = m;
            }

			count++;
		}

		System.out.println(count);
		in.close();
	}
}