C# StuckNumbers

using System;

class StuckNumbers
{
    static void Main()
    {
        int numbersCount = int.Parse(Console.ReadLine());
        string[] allNumbers = Console.ReadLine().Trim().Split();
        bool stuckNumbersExist = false;
        for (int i1 = 0; i1 < allNumbers.Length; i1++)
        {
            for (int i2 = 0; i2 < allNumbers.Length; i2++)
            {
                for (int i3 = 0; i3 < allNumbers.Length; i3++)
                {
                    for (int i4 = 0; i4 < allNumbers.Length; i4++)
                    {
                        if (i1 != i2 && i1 != i3 && i1 != i4 && i2 != i3 && i2 != i4 && i3 != i4)
                        {
                            string leftSide = "" + allNumbers[i1] + allNumbers[i2];
                            string rightSide = "" + allNumbers[i3] + allNumbers[i4];
                            if (leftSide == rightSide)
                            {
                                stuckNumbersExist = true;
                                Console.WriteLine("{0}|{1}=={2}|{3}", allNumbers[i1], allNumbers[i2], allNumbers[i3], allNumbers[i4]);
                            }
                        }
                    }
                }
            }
        }
        if (!stuckNumbersExist)
        {
            Console.WriteLine("No");
        }
    }
}