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 count = 0;
        int amnt = s;
        int k = 0;
        boolean flag = false;
        
        while(amnt > 0)
        {
            if(!flag)
            {
                amnt = amnt - p;
                if(amnt < 0)
                    return count;
                count++;            
                p = p - d;
                if(p < m)
                {
                    p = m;
                    flag = true;
                }
            } 
            else
            {
                amnt = amnt - p;
                if(amnt < 0)
                    return count;
                count++;            
            }
        }
        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();
    }
}