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

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		long[] Fib = new long[N+1];
		Fib[1] = 1;
		Fib[2] = 1;
		for(int i = 2;i<=N;i++){
			Fib[i] = Fib[i-1] + Fib[i-2];
		}
		
		long rem = Fib[N] - M;
		int cnt = 0;
		
		if( rem < 0 ){
			Console.WriteLine(-1);
			return;
		}
		
		for(int i=N-2;i>=1;i--){
			if( rem < Fib[i]) continue;
			rem -= Fib[i];
			cnt++;
			if(rem == 0) break;
		}
		
		if( rem != 0) {
			Console.WriteLine(-1);
			return;
		}
		
		Console.WriteLine(cnt);
	}
	int N;
	long M;
	public Sol(){
		var ss = rsa();
		N = int.Parse(ss[0]);
		M = long.Parse(ss[1]);
	}

	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(){return Console.ReadLine().Split(' ');}
	static int[] ria(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>int.Parse(e));}
	static long[] rla(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>long.Parse(e));}
	static double[] rda(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>double.Parse(e));}
}