#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i <= (n); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)

#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define show(x) cout << #x << " = " << x << endl
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define pii pair<int, int>
#define vi vector<int>

using namespace std;
template <class S, class T>
ostream& operator<<(ostream& o, const pair<S, T>& p)
{
    return o << "(" << p.first << "," << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& o, const vector<T>& vc)
{
    o << "sz = " << vc.size() << endl
      << "[";
    for (const T& v : vc)
        o << v << ",";
    o << "]";
    return o;
}
using ll = long long;
constexpr ll MOD = 1000000007;

constexpr int MAX = 81;
uint64_t fib[MAX];
bool check[MAX];

int seek(uint64_t v, int n)
{
    for (int i = n; i >= 1; i--) {
        if (v >= fib[i] and (not check[i])) {
            check[i] = true;
            return i;
        }
    }
    return -1;
}


int main()
{
    int N;
    cin >> N;
    uint64_t M;
    cin >> M;

    fib[1] = 1;
    fib[2] = 1;
    FOR(i, 3, 81)
    {
        fib[i] = fib[i - 1] + fib[i - 2];
    }
    uint64_t res = fib[N] - M;
    if (res > fib[N]) {
        cout << -1 << endl;
        return 0;
    }

    int cnt = 0;
    int n = N - 2;
    while (res > 0) {
        const int d = seek(res, n);
        if (d == -1) {
            cout << -1 << endl;
            return 0;
        }
        res -= fib[d];
        n = d - 1;
        cnt++;
    }

    cout << cnt << endl;

    return 0;
}