#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<stack>
#include<queue>
#include<vector>
#include<algorithm>
#include<string>
#include<iostream>
#include<set>
#include<map>
#include<bitset>

using namespace std;
typedef long long ll;
#define i_7 1000000007
#define i_5 1000000005

ll mod(ll a){
    ll c=a%i_7;
    if(c>=0)return c;
    else return c+i_7;
}
typedef pair<int,int> i_i;
typedef pair<ll,ll> l_l;
#define inf 100000000/*10^8*/
#define rep(i,l,r) for(int i=l;i<=r;i++)
const double EPS=1E-8;

////////////////////////////////////////


int main(){
    ll n,m;cin>>n>>m;
    ll dp[81];dp[1]=1;dp[2]=1;rep(i,3,80)dp[i]=dp[i-1]+dp[i-2];
    ll sum=dp[n]-m;
    int ans=0,pos=n-2;
    while(sum>0&&pos>=1){
        if(dp[pos]<=sum){
            sum-=dp[pos];
            ans++;
        }
        pos--;
    }
    if(sum!=0){
        cout<<-1;return 0;
    }
    cout<<ans<<endl;
    return 0;
}