#include <iostream>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = uint32_t;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

int main() {
    ll n, m;
    cin >> n >> m;
    vector<ll> fib(n, 1);
    for (int i = 2; i < n; ++i) {
        fib[i] = fib[i-1] + fib[i-2];
    }
    m = fib.back()-m;
    int ans = 0;
    for (int j = n-3; j >= 0; --j) {
        if(m >= fib[j]) m -= fib[j], ans++;
    }
    if(m) puts("-1");
    else cout << ans << "\n";
    return 0;
}