using System.Collections.Generic;
using System.Collections.Specialized;
using System.Formats.Asn1;
using System.Globalization;
using System.Linq;

namespace algorism
{
    class Program
    {
        static void Main()
        {
            /**/
            
            /**/
            string[] input1 = Console.ReadLine().Split(" ");
            int N = int.Parse(input1[0]);
            int A = int.Parse(input1[1]);
            int B = int.Parse(input1[2]);
            double ans = 0;
            for (int i = 0; i < N + 1; i++)
            {
                double nanika = double.Parse(Console.ReadLine()) / (i + 1);
                ans += (Math.Pow(B, i + 1) - Math.Pow(A, i + 1)) * (nanika);
            }
            long answer = (long)ans;
            Console.WriteLine(answer);
        }
    }
}