package yukicoder;
import java.util.Arrays;
import java.util.Scanner;
public class Main{
	public static void main(String[] args)throws Exception{
		new Main().solve();
	}
	long[] fibo;
	void solve(){
		Scanner sc=new Scanner(System.in);
		fibo=new long[81];fibo[1]=1;fibo[2]=1;
		for(int i=3;i<=80;i++)fibo[i]=fibo[i-1]+fibo[i-2];
		int n=sc.nextInt();
		long m=sc.nextLong();
		m=fibo[n]-m;
		int count=0;
		for(long i=n-2;i>=1;i--){
			if(fibo[(int)i]<=m){
				m-=fibo[(int)i];
				count++;
			}
			if(m==0)break;
		}
		if(m!=0)System.out.println(-1);
		else System.out.println(count);
	}
	void tr(Object...o){System.out.println(Arrays.deepToString(o));}
}