using System;

public class Program

{

    public static void Main()

    {

        String num = 1 + "", num2 = 1 + "";

        int counter = 2;

        while (num2.Length < 1000)

        {

            String num3 = Get2nums(num,num2);

            num = num2;

            num2 = num3;

            counter++;

        }

        Console.WriteLine(counter);

    }

    public static String Get2nums(String a, String b)

    {

        if (b.Length > a.Length)

        {

            String mid = b;

            b = a;

            a = mid;

        }

        int[] arr = new int[a.Length];

        for (int i=0;i<a.Length;i++)

        {

            arr[i] = a[i] - '0';

        }

        if (a.Length == b.Length)

        {

            for (int i=0;i<a.Length;i++)

            {

                arr[i] += b[i] - '0';

            }

        }

        else if (a.Length > b.Length)

        {

            for (int i = a.Length-1;i>=a.Length - b.Length;i--)

            {

                arr[i] += b[i- a.Length + b.Length] - '0';

            }

        }

        for (int i=a.Length-1;i>0;i--)

            {

                int num = arr[i];

                int Lnum = num % 10;

                int Pnum = arr[i-1];

                arr[i-1] = Pnum + num/10;

                arr[i] = Lnum;

            }

            String f = "";

            for (int i=0;i<a.Length;i++)

            {

                f = f + "" + arr[i];

            }

        return f;

    }

}