Stuck Numbers

/* You are given n numbers. Write a program to find among these numbers all sets of 4 numbers {a, b, c, d}, such that a|b == c|d, where a ≠ b ≠ c ≠ d. Assume that "a|b" means to append the number b after a. We call these numbers {a, b, c, d} stuck numbers: if we append a and b, we get the same result as if we appended c and d. Note that the numbers a, b, c and d should be distinct (a ≠ b ≠ c ≠ d).
 * Print at the console all stuck numbers {a, b, c, d} found in the input sequence in format "a|b==c|d" (without any spaces), each at a separate line. The order of the output lines is not important. Print "No" in case no stuck numbers exist among the input sequence of numbers. */

namespace _09.StuckNumbers
{
    using System;

    class StuckNumbers
    {
        private static bool _isFoundStuckNum = false;

        static void Main(string[] args)
        {
            int count = int.Parse(Console.ReadLine());
            string[] numbers = Console.ReadLine().Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);

            foreach (string a in numbers)
            {
                foreach (string b in numbers)
                {
                    if (b != a)
                    {
                        foreach (string c in numbers)
                        {
                            if (c != a && c != b)
                            {
                                foreach (string d in numbers)
                                {
                                    if (d != a && d != b && d != c)
                                    {
                                        CheckForStuckNumber(a, b, c, d);
                                    }
                                }
                            }
                        }
                    }
                }
            }

            if (!_isFoundStuckNum)
            {
                Console.WriteLine("No");
            }
        }

        private static void CheckForStuckNumber(string numA, string numB, string numC, string numD)
        {
            if ((numA + numB).Equals((numC + numD)))
            {
                _isFoundStuckNum = true;
                Console.WriteLine("{0}|{1}=={2}|{3}", numA, numB, numC, numD);
            }
        }
    }
}