Party Invitation

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace NLoopsPartyInvitation
{
    class NLoopsPartyInvitation
    {
        static void Main(string[] args)
        {
            string name = Console.ReadLine();

            int valid = 0;
            int invalid = 0;
            int counter = 0;




            while (name != "Statistic")
            {
                bool validName = true;
                counter++;

                foreach (char letter in name)
                {
                    if (letter >='a' && letter <='z' || letter >= 'A' && letter<='Z')
                    {
                        name = name.Substring(0, 1).ToUpper() + name.Substring(1).ToLower();


                    }
                    else
                    {
                        name = "Invalid name!";
                        validName = false;
                        break;
                    }

                }
                if (validName== false)
                {
                    invalid++;
                }

                Console.WriteLine(name);

                name = Console.ReadLine();
            }
            valid = counter - invalid;


            double percentValid = valid * 100.0/counter;
            double percentInvalid = invalid * 100.0 / counter;

            Console.WriteLine("Valid names are {0:f2}% from {1} names.",percentValid,counter);
            Console.WriteLine("Invalid names are {0:f2}% from {1} names.",percentInvalid,counter);



        }

    }
}