using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

using System.Xml;

using System.Xml.Linq;

using System.Globalization;

using System.Data;

using System.Data.DataSetExtensions;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        List<List<int>> FS=new List<List<int>>();

        FS.Add(new List<int>() {1,2,3});

        FS.Add(new List<int>() {5,7});

        FS.Add(new List<int>() {3,10});

        FS.Take(2).SelectMany(e=>e).Distinct().Dump();

​

    }

}

​

​