Largest 3 Rectangles

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

class UserLogs
{
    static void Main()
    {
        string input = Console.ReadLine();
        string pattern = @"]\s+";
        string[] substrings = Regex.Split(input, pattern);

        List<int> nums = new List<int>();
        for (int i = 0; i < substrings.Length; i++)
        {
            string[] numbers = Regex.Split(substrings[i], @"\D+");
            for (int i2 = 0; i2 < numbers.Length; i2++)
            {
                if (!string.IsNullOrEmpty(numbers[i2]))
                {
                    nums.Add(int.Parse(numbers[i2]));
                }
            }
        }
        List<int> res = new List<int>();
        for (int i3 = 0; i3 < nums.Count - 1; i3 += 2)
        {
            res.Add(nums[i3] * nums[i3 + 1]);
        }
        List<int> combine3 = new List<int>();
        for (int i4 = 0; i4 < res.Count - 2; i4++)
        {
            combine3.Add(res[i4] + res[i4 + 1] + res[i4 + 2]);
        }

        combine3.Sort((a, b) => -1 * a.CompareTo(b));

        Console.WriteLine(combine3[0]);
    }
}