using System.Runtime.ExceptionServices;

internal class Program
{

    //This program will enable a user to input their Surname, National Insurance Number,
    //and Age and each of the values will be displayed on the screen.
    private static void Main(string[] args) //Program Start Point
    {
        //VARIABLES
        string Forename; //Variable Forename declared as a string - Will store user's first name
        string Surname; //Variable Surname declared as a string - Will store user's last name
        string NINumber; //Variable NINumber declared as a string - Will store user's National Insurance number
        int Age; //Variable age declared as an integer - Will store the user's age



        //Forename
        Console.WriteLine("Please enter your First Name/ Forename: "); //Requests input from user
            Forename = Console.ReadLine(); //Gets input from user

        //Presence Check
        do
        {
            if (Forename.Length == 0)
            {
                Console.WriteLine("Error: Invalid entry!"); //Error message
                Console.WriteLine(" ");
                Console.WriteLine("Please enter your First Name/ Forename: "); //Requests input from user
                    Forename = Console.ReadLine(); //Gets input from user
            }
        }
        while (Forename.Length == 0);



        //Surname
        Console.WriteLine(" ");
        Console.WriteLine("Please enter your Last Name/ Surname: "); //Requests input from user
            Surname = Console.ReadLine(); //Gets input from user

        //Presence Check
        do
        {
            if (Surname.Length == 0)
            {
                Console.WriteLine("Error: Invalid entry!"); //Error message
                Console.WriteLine(" ");
                Console.WriteLine("Please enter your Last Name/ Surname: "); //Requests input from user
                    Surname = Console.ReadLine(); //Gets input from user
            }
        }
        while (Surname.Length == 0);



        //National Insurance (NI) Number
        Console.WriteLine(" ");
        Console.WriteLine("Please enter your National Insurance (NI) number (e.g. PE 25 34 12 B): "); //Requests input from user
            NINumber = Console.ReadLine(); //Gets input from user

        do
        {
            do
            {
                if (NINumber.Length == 0) //Presence Check
                {
                    Console.WriteLine("Error: Invalid Entry!"); //Error message
                    Console.WriteLine(" ");
                    Console.WriteLine("Please enter your National Insurance (NI) number: "); //Requests input from user
                        NINumber = Console.ReadLine(); //Gets input from user
                }
            }
            while (NINumber.Length == 0);

            do
            {
                if (NINumber.Length < 13) //Length Check
                {
                    Console.WriteLine("Error: NI Number entered is too short!"); //Error message
                    Console.WriteLine(" ");
                    Console.WriteLine("Please enter your National Insurance (NI) number: "); //Requests input from user
                        NINumber = Console.ReadLine(); //Gets input from user
                }
            }
            while (NINumber.Length < 13);

            do
            {
                if (NINumber.Length > 13) //Length Check
                {
                    Console.WriteLine("Error: NI Number entered is too long!"); //Error message
                    Console.WriteLine(" ");
                    Console.WriteLine("Please enter your National Insurance (NI) number: "); //Requests input from user
                        NINumber = Console.ReadLine(); //Gets input from user
                }
            }
            while (NINumber.Length > 13);
        }
        while (NINumber.Length != 13);



        //Age
        Console.WriteLine(" ");
        Console.WriteLine("Please enter your age (e.g. 24): "); //Requests input from user
            Age = Convert.ToInt32(Console.ReadLine()); //Gets input from user

        do
        {
            do
            {
                if (Age == 0) //Presence Check
                {
                    Console.WriteLine(" ");
                    Console.WriteLine("Error: Invalid Entry!"); //Error message
                    Console.WriteLine(" ");
                    Console.WriteLine("Please enter your age (e.g. 24): "); //Requests input from user
                        Age = Convert.ToInt32(Console.ReadLine()); //Gets input from user
                }
            }
            while (Age == 0);

            do
            {
                if (Age < 15)
                {
                    Console.WriteLine(" ");
                    Console.WriteLine("Error: You are not old enough to have a National Insurance Number!"); //Error message
                    Console.WriteLine(" ");
                    Console.WriteLine("Please enter your age (e.g. 24): "); //Requests input from user
                        Age = Convert.ToInt32(Console.ReadLine()); //Gets input from user
                }
            }
            while (Age < 15);

            do
            {
                if (Age > 101)
                {
                    Console.WriteLine(" ");
                    Console.WriteLine("Error: Invalid Entry!"); //Error message
                    Console.WriteLine(" ");
                    Console.WriteLine("Please enter your age (e.g. 24): "); //Requests input from user
                        Age = Convert.ToInt32(Console.ReadLine()); //Gets input from user
                }
            }
            while (Age > 101);

            if (Age > 14 && Age < 101)
            {
                break;
            }
        }
        while (Age !> 14 && Age !< 101); //Range Check



        //Display Values to the user
        Console.WriteLine(" ");
        Console.WriteLine("First Name/ Forename: " + Forename);
        Console.WriteLine("Last Name/ Surname: " + Surname);
        Console.WriteLine("National Insurance (NI) Number: " + NINumber);
        Console.WriteLine("Age: " + Age);

        Console.WriteLine(" ");
        Console.WriteLine("Please press enter to exit program");
        Console.ReadLine();
    }
}