Please help pass the test 6. It is very necessary.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _1910
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = Console.ReadLine();
            int n = int.Parse(str);
            string[] mas = Console.ReadLine().Split(' ');
            int[] a=new int[n];
            for (int i=0; i<n; i++)
                a[i]=int.Parse(mas[i]);
            int sum=0, j=0, maxsum=0;
            if (n >= 3)
            {
                for (int i = 0; i < n - 2; i++)
                {
                    if ((a[i] == a[i + 1]) && (a[i] == a[i + 2]))
                    {
                        sum = a[i]*3;
                        j = i + 2;
                    }
                    if (sum > maxsum)
                    {
                        maxsum = sum;
                        sum = 0;
                    }
                }
            }
            Console.WriteLine(maxsum + " " + j);
        }
    }
}