using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

public static class Program

{

    static ValueTuple<T, T> TwoOrDefault<T>(this IEnumerable<T> items, Comparer<T> comparator = null)

    {

        var c = comparator ?? Comparer<T>.Default;

        var start = new ValueTuple<T, T>(default, default);

        return items.Aggregate(start, (seed, source) =>

                               {

                                   seed.Item2 = c.Compare(source, seed.Item1) == 1

                                       ? seed.Item1

                                       : c.Compare(source, seed.Item1) == -1 && c.Compare(source, seed.Item2) == 1

                                           ? source

                                           : seed.Item2;

                                   seed.Item1 = c.Compare(source, seed.Item1) == 1 ? source : seed.Item1;

                                   return seed;

                               });

    }

    static T SecondOrDefault<T>(this IEnumerable<T> items, Comparer<T> comparator = null) {

        return items.TwoOrDefault<T>(comparator).Item2;

    }

    public static void Main()

    {

        int[] ints = {45, 100, 50, 100, 100, 55, 54, 58, 70, 100, 70, 69};

        var second1 = ints.SecondOrDefault();

        Console.WriteLine(second1);

        string[] strs = {"abs", "acc", "art", "amm", "ast"};

        var second2 = strs.SecondOrDefault();

        Console.WriteLine(second2);

    }

}