Array elements equal to their index

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _2.Array_Elements_Equal_to_Their_Index
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] input = Console.ReadLine().Split(' ');
            int[] numArray = new int[input.Length];
            int index = 0;
            string output = string.Empty;
            for (int i = 0; i < numArray.Length; i++)
            {
                numArray[i] = int.Parse(input[i]);
                if (numArray[i] == index)
                {
                    output += input[i] + " ";
                }
                index++;
            }
            Console.WriteLine(output);
        }
    }
}