#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define ll long long
#define rep(i,n) for(ll i=0;i<(n);i++)
#define pll pair<ll,ll>
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define ios ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define lb(c,x) distance(c.begin(),lower_bound(all(c),x))
#define ub(c,x) distance(c.begin(),upper_bound(all(c),x))
 
using namespace std;
 
template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
 
const int INF=1e9+7;

int main(){
    int times=0;
    int a,b;
    cin >> a >> b;
    int n=0;
    while(times<5){
        n=a*n+b;
        times++;
        if(n==0) break;
    }
    if(times==5){
        cout << -1 << endl;
    }
    else{
        cout << times << endl;
    }
    return 0;
}