#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr long long MOD = 1000000007;
int main(){
    ll a, b;
    cin >> a >> b;
    ll cnt = 0;
    ll tmp = 0;
    while (true) {
        tmp = a * tmp + b;
        cnt++;
        if (tmp == 0) break;
        if (cnt > 2e7) break;
    }
    if (cnt >= 2e7) cout << "-1" << endl;
    else
        cout << cnt << endl;
}