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 cost=0;
        int price=p;
        int count=0;
        while(cost<s)
        {
            count++;
            if(price>m)
            {    
                cost=cost+price;
                price=price-d;
            }
            else
            {
                cost=cost+m;
            }               
        }    
        if(cost>s)
            return count-1;
        else
            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();
    }
}