using System;
     
    namespace For39262
    {
        internal class Program
        {
            private static void Main(string[] args)
            {
                Console.WriteLine("Here we go...");
     
                int[] A = new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 };
                int K = 3;
                
     			if ((K<1) || (K>A.Length) )
     			{
     				Console.WriteLine("error on input data");
     				Console.Read();
     				return;
     			}
			     
     			for(int i=K;i<A.Length; i+=K) Console.WriteLine(A[i]);
                Console.Read();
            }
     
            
    

        }
    }