#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <complex>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <iomanip>
#include <assert.h>
#include <array>
#include <cstdio>
#include <cstring>
#include <random>
#include <functional>
#include <numeric>
#include <bitset>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)
#define all(c) (c).begin(), (c).end()
#define zero(a) memset(a, 0, sizeof a)
#define minus(a) memset(a, -1, sizeof a)
#define minimize(a, x) a = std::min<decltype(a)>(a, x)
#define maximize(a, x) a = std::max<decltype(a)>(a, x)

typedef long long ll;
int const inf = 1<<29;

int main() {

  ll N, M; cin >> N >> M;

  ll fib[88]; fib[0] = fib[1] = 1;

  REP(i, 2, 88) fib[i] = fib[i-1] + fib[i-2];

  ll diff = fib[N-1] - M;
  int res = 0;
  for(int i=N-1; i>=0; i--) {
    if(fib[i] <= diff) {
      diff -= fib[i];
      res ++;
    }
  }
  
  cout << ( !!diff ? -1 : res ) << endl;
  
  return 0;
}