using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var listA = new List<int>{1,2,3};

        var listB = new List<int>{4,5,6};

        var combined = listA.Zip(listB, (a,b) => new List<int>{a,b}).ToList();

        foreach(var item in combined)

            Console.WriteLine(String.Join(",",item));

    }

}