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 t=p,sum=0,g=0;
            /*if(s>t)
            {
                g++;
                sum+=t;
                
            }*/
            while( sum<=s  )
            {
                //System.out.println(t);
                //1System.out.println("s="+sum);
                sum+=t;
                g++;
                if(sum>s)
                {
                    g--;
                    sum-=t;
                    break;
                }
                //g++;
                //if(t>m)
                if(t-d<=m)
                    t=m;
                else
                    t-=d;
               
            }
           //System.out.println("s2="+sum);
        return g;
    }

    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();
    }
}