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();
        int d = in.nextInt();
        int m = in.nextInt();
        int s = in.nextInt();
        int sum=0;
        int c=0;
        sum=sum+p;
        while(sum<=s)
        {
            p=p-d;
            if(p<=m)
            {
                sum=sum+m;
                c++;
            }
            else
            {
            sum=sum+p;
         
                c++;
            }
        }
        System.out.println(c);
        
        
    }
}