package Problem25;
import java.math.*;
public class Lösung
{
	public static void main(String[] args)
	{
		System.out.println(test());
	}
	static BigInteger a = new BigInteger("1");
	static BigInteger b = new BigInteger("1");
	static int max = 1_000_000;

	static public int test()
	{
		int i = 1;
		while(i < max)
		{
			a = a.add(b);
			b = b.add(a);
			if(getWritableNumber(a) == true)
				return i+2 ;
			if(getWritableNumber(b) == true)
				return i+3;
			i += 2;
		}
		return -1;
	}

	static public boolean getWritableNumber(BigInteger number)
	{
		boolean res = false;
	    int digitSize = 0;
	    while (!number.equals(BigInteger.ZERO))
	    {
	        number = number.divide(BigInteger.TEN);
	        digitSize++;
	    }
	    if(digitSize >= 1000)
	    	res = true;
	    return res;
	}

}