using System;
using System.Numerics;
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]);
            BigInteger temp = 0;
            long ans = 0;
            long dekai = 1;
            for (int i = 1; i <= N + 1; i++) dekai *= i;
            for (int i = 0; i < N + 1; i++)
            {
                long nanika = long.Parse(Console.ReadLine());
                long kaijyou = dekai / (i + 1);
                temp += ((long)Math.Pow(B, i + 1) - (long)Math.Pow(A, i + 1)) * (nanika) * kaijyou;
            }
            ans = (long)((temp - (temp % dekai)) / dekai);
            Console.WriteLine(ans);
        }
    }
}