using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        int[] snew = {1,2,3,1};

        snew = snew.GroupBy(x => x).Where(x => x.Count() == 1).Select(x => x.First()).ToArray();

        Console.WriteLine(string.Join(", ", snew));

    }

}