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 count=0,sum=0;
        for(int i=p;i>0;)
        {
            sum+=i;
            if(i>m)
            {
                
                
                if(i-d>=m)
                    i-=d;
                else
                    i=m;
            }
            
            if(sum>s)
                break;
            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();
    }
}