using System;

using System.Collections.Generic;

using System.Collections;

public class Program

{

    public static void Main()

    {

        var array = new int[] {1, 4, 5, 3, 2};

        var sum = 5;

        PrintTwoSum(array, sum);

    }

    public static void PrintTwoSum(int[] array, int sum)

    {

        var hashtable = new Hashtable();

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

            int complement = sum - array[i];

            if (hashtable.ContainsKey(complement)) 

            {

                return new int[] { hashtable[i], i };

            }

            hashtable.Add(array[i], i);

        }

    }

}