import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	
	public static long MOD = 1000000007;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		final long M = sc.nextLong();
		
		long[] fibs = new long[N];
		fibs[0] = fibs[1] = 1;
		for(int i = 2; i < N; i++){
			fibs[i] = fibs[i - 1] + fibs[i - 2];
		}
		
		if(fibs[N - 1] < M){
			System.out.println(-1);
			return;
		}
		
		// 貪欲で良い理由がよく分からない。
		long remain = fibs[N - 1] - M;
		int count = 0;
		for(int i = N - 2; i >= 0; i--){
			if(remain >= fibs[i]){
				//System.out.printｈln(remain + " " + fibs[i]);
				remain -= fibs[i];
				count++;
			}
		}
		
		System.out.println(count);
	}
}