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

using ll = long long;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  ll a, b, n = 0;
  cin >> a >> b;
  
  ll ans = 0;
  for (int i = 1; i <= 10000000; i++) {
    n = a * n + b;
    if (n == 0) {
      cout << i << '\n';;
      return 0;
    }
  }
  
  cout << "-1\n";
  return 0;
}