using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SumProduct
{
    class Program
    {

        static void Print(int idx, int[,] dp, int b, int c)
        {
            for (int i = b; i <= c; i++)
            {
                Console.Write(dp[idx, i]+" ");
            }
            Console.WriteLine();
        }

        static void Main(string[] args)
        {
            int[] input = Console.ReadLine().Split(' ').
                Select(int.Parse).ToArray();
            int n = input[0];
            int b = input[1];
            int c = input[2];
            int d = input[3];

            int[] a = Console.ReadLine().Split(' ').
                Select(int.Parse).ToArray();

            int[,] dp = new int[2, 10];

            for (int i = b; i <= c; i++)
            {
                dp[0, i] = a[0] * i;
            }

            int max = int.MinValue;

            for (int i = 1; i < n; i++)
            {

                    for (int currentMul = b; currentMul <= c; currentMul++)
                    {
                        if (i % 2 != 0)
                        {
                            max = int.MinValue;
                            for (int prevMul = b; prevMul <= c; prevMul++)
                            {
                                if (Math.Abs(currentMul - prevMul) <= d
                                    && dp[0, prevMul] > max)
                                    max = dp[0, prevMul];
                            }
                            dp[1, currentMul] = max + a[i] * currentMul;
                        }
                        else
                        {
                            max = int.MinValue;
                            for (int prevMul = b; prevMul <= c; prevMul++)
                            {
                                if (Math.Abs(currentMul - prevMul) <= d
                                    && dp[1, prevMul] > max)
                                    max = dp[1, prevMul];
                            }
                            dp[0, currentMul] = max + a[i] * currentMul;
                        }
                }
            }

            int ans = int.MinValue;
            if (n % 2 != 0)
            {
                //0
                for (int i = b; i <= c; i++)
                {
                    ans = Math.Max(ans, dp[0, i]);
                }
            }
            else {
                //1
                for (int i = b; i <= c; i++)
                {
                    ans = Math.Max(ans, dp[1, i]);
                }
            }

            Console.WriteLine(ans);
        }
    }
}