Update 10.Join Lists

using System;
using System.Collections.Generic;
using System.Linq;

class Lists
{
    static void Main()
    {
        Console.Write("Enter the number of numbers in the first list:");
        int firstN = int.Parse(Console.ReadLine());
        Console.WriteLine("\n");
        Console.Write("Enter the number of numbers in the second list:");
        int secondN = int.Parse(Console.ReadLine());
        Console.WriteLine("\n");

        List<int> firstList = new List<int>();
        Console.WriteLine("Enter {0} elements of first List:",firstN);
        for (int i = 0; i < firstN; i++)
        {
            int numInt = int.Parse(Console.ReadLine());
            firstList.Add(numInt);
        }
        Console.WriteLine("\n");
        List<int> secondList = new List<int>();
        Console.WriteLine("Enter {0} elements of second List:",secondN);
        for (int i = 0; i < secondN; i++)
        {
            int numInt = int.Parse(Console.ReadLine());
            secondList.Add(numInt);
        }
        Console.WriteLine("\n");
        List<int> combineList = Combine(firstN,secondN,firstList,secondList);
        IEnumerable<int> distinctCombine = combineList.Distinct();
        //Method returns an unordered sequence that contains no duplicate values. 
        PrintList(distinctCombine);
    }
     static List<int> Combine(int first,int second,
                List<int> firstList, List<int> secondList)
    {
        if (first <= 0 || second <= 0)
        {
            throw new ArgumentOutOfRangeException("Number of numbers can not be negative or zero!");
        }
        List<int> combine = new List<int>();

        combine.AddRange(firstList);

        foreach (var item in secondList)
        {
            if (!combine.Contains(item))
            {
                combine.Add(item);
            }
        }
        combine.Sort();
        return combine;
    }
     static void PrintList(IEnumerable<int> distinctCombine)
     {
         foreach (var item in distinctCombine)
         {
             Console.Write(item);
             Console.Write(" ");
         }
         Console.WriteLine("\n");
     }
   
}