using System;

using System.Collections.Generic;

using System.Linq;

public class WO

    {

        public string Id {get;set;}

        public string WOOp {get;set;}

    }

​

public class Program

{

    public static void Main()

    {

        List<WO> lista = new List<WO>();

        lista.Add(new WO(){Id="WO1", WOOp = "WO1OP1"});

        lista.Add(new WO(){Id="WO1", WOOp = "WO1OP2"});

        lista.Add(new WO(){Id="WO1", WOOp = "WO1OP3"});//commentami

        lista.Add(new WO(){Id="WO2", WOOp = "WO2OP1"});

        lista.Add(new WO(){Id="WO2", WOOp = "WO2OP2"});

        lista.Add(new WO(){Id="WO3", WOOp = "WO3OP1"});

        lista.Add(new WO(){Id="WO3", WOOp = "WO3OP2"});

        foreach (WO wo in lista)

        {

            Console.WriteLine(wo.Id + "-" + wo.WOOp);

        }

        Console.WriteLine();

        Console.WriteLine(lista.GroupBy(x => x.Id).Select(o => o.Count()).Distinct().Count());

    }

}

​

​