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 n=p,c=p,i=1,j=1;
        while(n<=s)
        {
            if(c<=m)
        {
            i++;
            c=m;}
         else 
         { 
         j++;
         c=p-d;}
       n=n+c; 
        }
        return i+j;
    }

    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();
    }
}