gistfile1.txt

static bool CheckBad(int[] a)
        {
            for (int i = 0; i < a.Length; i++)
                if (a[i] != i)
                    return false;
            return true;
        }       

if (N >= 2)
            {
                int[] nums = new int[N];
                for (int i = 0; i < N; i++)
                {
                    nums[i] = i;
                }
                do
                {
                    Shuffle(nums);
                } while (CheckBad(nums));

                if (true)
                {
                    for (int i = 0; i < nums.Length; i++)
                    {
                        Console.WriteLine("Person #" + (i + 1) + " should buy a gift for Person #" + (nums[i] + 1));
                    }
                }
            }