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 remainingMoney = s;
        int currentPrice = p;
        int numGames = 0;
        boolean limitHit = false;
        
        //can still purchase
        while((remainingMoney-currentPrice)>=0){
            //purchase
            numGames++;
            remainingMoney -= currentPrice;
            if(!limitHit && (currentPrice-d)>m){
                currentPrice -= d;
            }
            else{
                limitHit = true;
                currentPrice = m;
            }
        }
        return numGames;
        
    }

    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();
    }
}