using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Collections;  

public class Program

{

    public class Student

    { 

        public int StudentID { get; set; }

        public string StudentName { get; set; }

        public int Age { get; set; }        

    }       

    public static void Main()

    {

        IList<Student> studentList = new List<Student>() 

        { 

            new Student() { StudentID = 1, StudentName = "John", Age = 13 },

            new Student() { StudentID = 2, StudentName = "Moin",  Age = 21 },

            new Student() { StudentID = 3, StudentName = "Bill",  Age = 18 },

            new Student() { StudentID = 4, StudentName = "Ram", Age = 20 },

            new Student() { StudentID = 5, StudentName = "Ron", Age = 15 } 

        };

​

        var oldest = studentList.Max(s => s.Age);

​

        Console.WriteLine("Oldest Student Age: {0}", oldest);

    }

}