using System;

using System.Linq;

​

namespace Zonal

{

    public class Program

    {

        public static int Solution(int[] input)

        {

            Array.Sort(input);

            int index = 0;

            while (index < input.Length && input[index] < 1)

                index++;

            int expected = 1;

            while (index < input.Length)

            {

                if (input[index] > expected)

                    return expected;

                while (index < input.Length && input[index] == expected)

                    index++;

                expected++;

            }

​

            return expected;

        }

​

        public static void Main()

        {

            var arr = new int[]{1, 3, 6, 4, 1, 2};

            var low = arr.Min();

            var high = arr.Max();

            if (arr.Length < 100000 && low > -1000000 && high < 1000000)

            {

                Console.WriteLine(Solution(arr));

            }

​

            var arr1 = new int[]{1, 2, 3};

            var low1 = arr1.Min();

            var high1 = arr1.Max();

            if (arr1.Length < 100000 && low1 > -1000000 && high1 < 1000000)

            {

                Console.WriteLine(Solution(arr1));

            }

​

            var arr2 = new int[]{-1, -3};

            var low2 = arr2.Min();

            var high2 = arr2.Max();

            if (arr2.Length < 100000 && low2 > -1000000 && high2 < 1000000)

            {

                Console.WriteLine(Solution(arr2));

            }

        }

    }

}