#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector< int > vi;
typedef vector< vi > vvi;
typedef vector< ll > vl;
typedef vector< vl > vvl;
typedef pair< int, int > pii;
typedef vector< pii > vp;
typedef vector< double > vd;
typedef vector< vd > vvd;
typedef vector< string > vs;

template< class T1, class T2 >
int upmin( T1 &x, T2 v ){
  if( x > v ){
    x = v;
    return 1;
  }
  return 0;
}

template< class T1, class T2 >
int upmax( T1 &x, T2 v ){
  if( x < v ){
    x = v;
    return 1;
  }
  return 0;
}

const int INF = 0x3f3f3f3f;

int N;
ll M;

void init(){
  cin >> N >> M;
}

vl fib;

void preprocess(){
  fib = vl( 80 + 1 );
  fib[ 1 ] = fib[ 2 ] = 1;
  for( int i = 3; i <= 80; ++i )
    fib[ i ] = fib[ i - 1 ] + fib[ i - 2 ];
  if( fib[ N ] < M )
    cout << -1 << endl, exit( 0 );
}

void solve(){
  ll diff = fib[ N ] - M;
  int ans = 0;
  int k = 1;
  while( fib[ k - 1 ] + fib[ k ] <= diff )
    ++k;
  k = min( k, N - 2 );
  while( diff ){
    ++ans;
    diff -= fib[ k-- ];
    while( fib[ k ] > diff )
      --k;
  }
  cout << ans << endl;
}

signed main(){
  ios::sync_with_stdio( 0 );
  init();
  preprocess();
  solve();
  return 0;
}