import java.net.NetworkInterface;
import java.util.*;

public class Main {public static int upper_bound(long[] arr, long key) {
	int len = arr.length;
	int lo = 0;
	int hi = len-1;
	int mid = (lo + hi)/2;
	while (true) {
		long cmp = arr[mid]-key;
		if (cmp == 0 || cmp < 0) {
			lo = mid+1;
			if (hi < lo)
				return mid<len-1?mid+1:-1;
		} else {
			hi = mid-1;
			if (hi < lo)
				return mid;
		}
		mid = (lo + hi)/2;
	}
}
	static long gcd(long a,long b){
		return b == 0 ? a : gcd(b, a%b);
	}
	static long lcm(long a, long b){
		return a*b/gcd(a, b);
	}
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long m = sc.nextLong();
		if(m<1){ System.out.println(-1);
		return;}
		long[] fib = new long[100];
		fib[0]=1;fib[1]=1;
		for(int i=2;i<100;i++) fib[i]=fib[i-1]+fib[i-2];
		long sa = fib[n-1]-m;
		if(sa==0){
			System.out.println(0);
			return;
		}else if(sa<0){
			System.out.println(-1);
			return;
		}
		int ans = 0;
		long[] aaa = new long[n-2];
		aaa[0]=1;
		aaa[1]=1;
		for(int i=2;i<n-2;i++) aaa[i]=aaa[i-1]+aaa[i-2];
		while(sa>0){
			int x = upper_bound(aaa, sa)-1;
			if(x<0) x=n-3;
			sa-=aaa[x];
			aaa[x]=1;
			Arrays.sort(aaa);
			ans++;
		}
		System.out.println(ans);
	}
}