#pragma GCC optimize("O3")
#include <bits/stdc++.h> 
using namespace std;
using ll=long long;
//using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
//const ll mod=998244353;
const ll mod=1000000007;
ll GCD(ll a,ll b) {return b ? GCD(b,a%b):a;}
ll LCM(ll c,ll d){return c/GCD(c,d)*d;}
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
using lll=__int128_t;
int main(){
    ll a,b;
    cin>>a>>b;
    if(b==0){
        cout<<1<<"\n";
        return 0;
    }
    if(a==0||abs(b)%abs(a)!=0||a>0&&b>0){
        cout<<-1<<"\n";
        return 0;
    }
    if(a==b&&abs(a)!=1){
        cout<<-1<<"\n";
        return 0;
    }
    ll g=GCD(abs(a),abs(b));
    a/=g;b/=g;
    lll t=-b/a;
    lll v=0;
    for(int i=0;i<10;i++){
        if(v==t){
            cout<<i+1<<"\n";
            return 0;
        }
        v=lll(a)*v+lll(b);
    }
    cout<<-1<<"\n";
}