#ifdef __GNUC__
#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#endif

#define _USE_MATH_DEFINES

#include <iostream>
#include <iomanip>
#include <stdio.h>

#include <sstream>
#include <algorithm>
#include <cmath>

#include <string>
#include <cstring>
#include <vector>
#include <valarray>
#include <array>

#include <queue>
#include <complex>
#include <set>
#include <map>
#include <stack>
#include <list>

#include <cassert>//assert();
#include <fstream>
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)

/////////
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
#define PII pair<int,int>
/////////
using namespace::std;

// 最大公約数
template<class T>
inline T gcd(T a, T b){return b == 0 ? a : gcd(b, a % b);}
// 最小公倍数
template<class T>
inline T lcm(T a, T b){return a * b / gcd(a, b);}
////////////////////////////////
vector<ULL> fib;
void makeFib(int N){
	fib = vector<ULL>(N+1);
	fib[1] = 1;
	fib[2] = 1;
	for(int i=3;i<=N;++i){
		fib[i] = fib[i-1]+fib[i-2];
	}
}
inline void solve(){
	int N;
	ULL M;
	cin >> N >> M;
	makeFib(N);
	if( fib[N] < M ){//M大きすぎ
		cout << -1 << endl;
		return;
	}
	//[N-2,2]
	ULL sa = fib[N] - M;
	int ans = 0;
	int i;
	while(sa>0){
		for(i=N-2;i>1;--i){
			if( sa >= fib[i] ){
				sa -= fib[i];
				++ans;
				break;
			}
		}
		if( i == 1 ){
			cout << -1 << endl;
			return;
		}
	}
	cout << ans << endl;
}

signed main(void){
	std::cin.tie(0);
	std::ios::sync_with_stdio(false);
	//std::cout << std::fixed;//小数を10進数表示
	//cout << setprecision(16);//小数をいっぱい表示する。16?

	solve();
}