using System;

using System.Linq;

using System.Collections.Generic;

​

public class Simple {

    public class Persona{

        public int Id {get; set;}

        public string Nombre {get; set;}

    }

  public static void Main() {

    List<Persona> persons = new List<Persona>();

      persons.Add(new Persona{

          Id=1,

          Nombre="Walter"         

      });

      persons.Add(new Persona{

          Id=2,

          Nombre="Isabel"         

      });

      persons.Add(new Persona{

          Id=3,

          Nombre="Ronny"          

      });

      var person = persons.Max(p=>p.Id);

      Console.WriteLine(person);

  }

}