using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        int[] c0 = new int[] {0, 1, 0, 2, 3, 4, 5, 1, 6}; 

        int[] c1 = new int[] {0, 1, 3}; 

        var f = c1.SelectMany(v0 => c0.Where(v1 => v0 == v1));

        foreach(var c in f)

            Console.WriteLine(c);

    }

}