using System;  

public class InvalidAgeException : Exception  

{  

    public InvalidAgeException(String message)  

        : base(message)  

    {  

    }  

}  

public class Test1  

{  

    static void validate(int age)  

    {  

        if (age < 18)  

        {  

            throw new InvalidAgeException("Sorry, Age must be greater than 18");  

        }  

    }  

    public static void Main(string[] args)  

    {  

        try  

        {  

            validate(12);  

        }  

        catch (InvalidAgeException e) { Console.WriteLine(e); }  

​

    }  

}