#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
using namespace std;

#define REP(i,s,e) for (i = s; i <= e; i++)
#define rep(i,n) REP (i,0,(int)(n)-1)
#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP (i,(int)(n)-1,0)
#define INF (int)1e8
#define MOD (int)(1e9+7)

typedef long long ll;

ll fib[80];

int main(void) {
    int i, N;
    ll M;
    cin >> N >> M;
    N--;
    fib[0] = fib[1] = 1;
    REP (i,2,N) fib[i] = fib[i-1] + fib[i-2];
    M = fib[N] - M;
    int ans = 0;
    while (M) {
        i = 0;
        while (i < N-2 && fib[i+1] <= M) i++;
        M -= fib[i];
        fib[i] = 1e18;
        ans++;
        if (ans > N) {
            cout << -1 << endl;
            return 0;
        }
    }
    cout << ans << endl;
    return 0;
}