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[] F=new long[N+1];
		F[1]=1;F[2]=1;
		for(int i=3;i<=N;i++){
			F[i]=F[i-1]+F[i-2];
		}
		int cnt=0;
		if(F[N]<M){
			Console.WriteLine(-1);
			return;
		}
		if(F[N]==M){
			Console.WriteLine(0);
			return;
		}
		
		M=F[N]-M;
		for(int i=N-2;i>0;i--){
			if(M>=F[i]){
				M-=F[i];
				cnt++;
			}
		}
		Console.WriteLine(M==0?cnt:-1);
	}
	int N;
	long M;
	public Sol(){
		var d=rla();
		N=(int)d[0];M=d[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));}
}