using System;

namespace Example76
{
	/// <summary>
	/// Summary description for Class1.
	/// </summary>
	class Class1
	{
		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main(string[] args)
		{
			Console.Write("Input a string: ");
			string s = Console.ReadLine();
			Console.WriteLine("Is {0} a variable name? {1}",
				s, IsVariable(s));
		}

		static bool IsVariable(string s)
		{
			if (s.Length == 0)
				return false;
			else
			if (Char.IsLetter(s[0]))
				return IsVariable2(s.Remove(0, 1));
			else
				return false;
		}

		static bool IsVariable2(string s)
		{
			if (s.Length == 0)
				return true;
			else
			if (Char.IsLetter(s[0]) || Char.IsDigit(s[0]))
				return IsVariable2(s.Remove(0, 1));
			else
				return false;
		}
	}
}