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 ans=0;
        int cost = p;
        
        while((s-cost)>=0){
            s -= cost;
                if(cost-d<=m)
                    cost = m;
                else
                    cost -= d;
            ans++;
            //System.out.print(cost + "  ");
        }
        return ans;
    }

    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();
    }
}