using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static long NN => long.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var x = NN;
        var a = NN;
        var b = NN;
        var max = 1L << (int)n - 1;
        WriteLine(Math.Min((x + a - 1) / a, (max - x + b - 1) / b));
    }
}