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

    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();
    }
}