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 sum=p;
        int price=p;
        int count=0;
        if(p<=s){
        count=1;
        while(sum<=s){
            int i=0;
            if(price>m){
                price=price-d;
                if(price<m){
                    price=m;
                }
                if(sum+price<=s){
                    sum=sum+price;
                    count++;
                    i++;
                }
            }
            else if(price<=m && sum+price<=s){
                sum=sum+price;
                count++;
                i++;
            }
            if(i==0){
                break;
            }
        }
        }
        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();
    }
}