Variant №1 1-masala

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Linq;
namespace M_ish_3
{
public class Talaba
{
public int ID;
public string FIO;
public string Manzil;
public int Yoshi;
public string GuruhID;

}
public partial class Window1 : Window

{
public Window1()
{
InitializeComponent();
a=new List();
}
Lista;
void Form_Loaded(object sender, RoutedEventArgs e)
{
a.Add(new Talaba{ID=1,FIO="Abdujabborov D",Manzil="Rishton tumani",Yoshi=19,GuruhID="21.06"});
a.Add(new Talaba{ID=2,FIO="Mamasharipov F",Manzil="Rishton tumani",Yoshi=19,GuruhID="21.07"});
a.Add(new Talaba{ID=3,FIO="Xolmatov M",Manzil="Buvayda tumani",Yoshi=20,GuruhID="21.07"});
a.Add(new Talaba{ID=4,FIO="Sheraliyev X",Manzil="Toshloq",Yoshi=21,GuruhID="21.08"});
a.Add(new Talaba{ID=5,FIO="Abdurahimov Y",Manzil="Qo'qon shahri",Yoshi=22,GuruhID="21.10"});
a.Add(new Talaba{ID=6,FIO="Ergashev Sh",Manzil="Rishton tumani",Yoshi=15,GuruhID="21.15"});
a.Add(new Talaba{ID=7,FIO="Halimov Y",Manzil="Bag'dod tumani",Yoshi=25,GuruhID="21.20"});
a.Add(new Talaba{ID=8,FIO="Hoshimov J",Manzil="Beshariq tumani",Yoshi=27,GuruhID="21.22"});
a.Add(new Talaba{ID=9,FIO="Sheraliyev J",Manzil="Oltiariq tumani",Yoshi=15,GuruhID="21.17"});
a.Add(new Talaba{ID=10,FIO="Muxtorov O",Manzil="Uchko'prik tumani",Yoshi=18,GuruhID="21.06"});
}
void jadval_Loaded(object sender, RoutedEventArgs e)
{
var s=
from n in a