import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long m = sc.nextLong();
		long[] fibo = new long[n + 1];
		fibo[1] = 1;
		fibo[2] = 1;
		for (int i = 3; i <= n; i++) {
		    fibo[i] = fibo[i - 1] + fibo[i - 2];
		}
		long diff = fibo[n] - m;
		if (diff < 0) {
		    System.out.println(-1);
		    return;
		}
		int count = 0;
		for (int i = n - 2; i >= 0 && diff > 0; i--) {
		    if (diff >= fibo[i]) {
		        count++;
		        diff -= fibo[i];
		    }
		}
		if (diff > 0) {
		    System.out.println(-1);
		} else {
		    System.out.println(count);
		}
	}
}