Find the closest Fibonacci number

Fibonachi.cs

using System;
using System.Collections.Generic;

namespace Fibonachi
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Number: ");
            int i = int.Parse(Console.ReadLine());
            Console.WriteLine("Closest Fibonachi is: {0}", ClosestFibonacci(i));

            Console.ReadLine();
        }
        static int ClosestFibonacci(int num)
        {
            if (num < 1)
            {
                return 0;
            }
            else if (num == 1)
            {
                return 1;
            }
            else
            {
                List<int> Fibonachi = new List<int>();
                Fibonachi.Add(1);
                Fibonachi.Add(1);
                while (true)
                {
                    int index = Fibonachi.Count;
                    Fibonachi.Add(Fibonachi[index - 1] + Fibonachi[index - 2]);
                    if (Fibonachi[Fibonachi.Count - 1] > num)
                    {
                        break;
                    }
                }
                return Fibonachi[Fibonachi.Count - 2];
            }
        }
    }
}