import java.util.Scanner;

/**
 * Created by Yurii on 9/9/2017.
 */
public class Solution {

        static int howManyGames(int p, int d, int m, int s) {
            int numbers = 0;
            int cost = p;

            while( s >= cost){
                s-=cost;
                numbers ++;
                if(cost-d>m)
                    cost-=d;
                else
                    cost = m;

            }
            return numbers;
        }

        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();
        }


}