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) {
        // Return the number of games you can buy
        int cost = 0 , count = 0 , t = 0 ;
        if(p > s) return count;
        else
        {
            cost += p ;
            count++;
        }
        while(cost <= s)
        {
            p -= d ;
            if(p < m) p = m ;
            if(p >= m)
            {
                 t += p ;
                if(t <= s)
                {
                    cost += p ;
                    count ++;
                }
                else break;
            }
        }
        return(count-1);
    }

    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();
    }
}