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 numGames = 0;
        int money = s;
        int nextCost = p;
        
        // While we still have money to buy one more game...
        while (money >= nextCost) {
            
            // Buy the game
            money -= nextCost;
            numGames++;
            
            // Calculate cost of next game
            if (nextCost > m) {
                nextCost = Math.max(nextCost - d, 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();
    }
}