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 c=0;
        
        while(s>=m)
        {
            if(s>=p && p>=m)
            {
                s -= p;
                c++;
                p -= d;
            }
            else if(p<=m)
            {
                c += s/m;
                break;
            }
            else
                break;
        }
        return c;
    }

    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();
    }
}