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 output  = 0;
		int currentTicketPrice = p;
		
		for(;(s>0&&s>=currentTicketPrice);)
		{
			output++;
			s=s-currentTicketPrice;
			if(currentTicketPrice>0 && (currentTicketPrice-d) >= m ) {
				currentTicketPrice = currentTicketPrice - d;
			}
			else {
				currentTicketPrice = m;
				break;
			}
		}
		
		if(currentTicketPrice>0 && s>0) {
			output = output + (s/currentTicketPrice);
		}
		return output;
    }

    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();
    }
}