#include <bits/stdc++.h>

using ll = long long;

using namespace std;

int main()
{
        ios::sync_with_stdio(false);
        cin.tie(nullptr);

        int cnt{ 0 };
        ll a, b, n{ 0 };
        cin >> a >> b;

        if (a == 0 && b != 0)
        {
            cout << "-1\n";
            return 0;
        }

        while (1)
        {
            if ((a * n > 0 && b > 0) || (a * n < 0 && b < 0))
            {
                cnt = -1;
                break;
            }

            n = a * n + b;
            ++cnt;
            if (!n)
                break;
        }

        cout << cnt << "\n";
    
    return 0;
}