Sets & Dictionaries Advanced - 02. Sets of Elements

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace Advanced
{
    class Program
    {
        static void Main(string[] args)
        {
            var firstSet = new HashSet<string>();
            var secondSet = new HashSet<string>();

            var setsSize = Console.ReadLine()
                .Split()
                .Select(int.Parse)
                .ToArray();

            for (int i = 0; i < setsSize.Sum(); i++)
            {
                var element = Console.ReadLine();

                if (i < setsSize[0])
                {
                    firstSet.Add(element);
                }

                else
                {
                    secondSet.Add(element);
                }
            }

            Console.WriteLine(string.Join(" ", firstSet.Where(x => secondSet.Contains(x))));
        }
    }
}