using System;

using System.Collections.Generic;

public class Program

{

    static public int[] GenerateArray(int count) {

        var array = new int[count];

        var rnd = new Random();

        for (int i = 0; i < count; i++)

        {

            array[i] = rnd.Next(-100, 100);

        }

        return array;

    }

    static public List<KeyValuePair<int, int>> FindPair(int[] array, int m)

    {

        var result = new List<KeyValuePair<int, int>>();

        var dict = new Dictionary<int, List<int>>();

        for (int i = 0; i < array.Length; i++)

        {

            int temp = m - array[i];

            if (dict.ContainsKey(temp)) {

                foreach(var item in dict[temp])

                {

                    result.Add(new KeyValuePair<int, int>(i, item));

                }

            }

            if (dict.ContainsKey(array[i]))

            {

                dict[array[i]].Add(i);

            }

            else

            {

                dict.Add(array[i], new List<int> { i });

            }

        }

        return result;

    }

    public static void Main()

    {

        var array = GenerateArray(1000);

        var result = FindPair(array, 10);

        foreach(var item in result){

            Console.WriteLine("Pair: {0}({1}) - {2}({3})", item.Key, array[item.Key], item.Value, array[item.Value]);

        }

    }

}