#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
#define int ll

#define REP(i,n) for(int i=0;i<n;++i)
#define ALL(name) name.begin(),name.end()
#define SORT(name) sort(name.begin(), name.end())
#define ZERO(p) memset(p, 0, sizeof(p))
#define MINUS(p) memset(p, -1, sizeof(p))
#if 1
#  define DBG(fmt, ...) printf(fmt, ##__VA_ARGS__)
#else
#  define DBG(fmt, ...)
#endif

const ll LLINF = (1LL<<60);
const int INF = (1LL<<30);
const double DINF = std::numeric_limits<double>::infinity();
const int MOD = 1000000007;
#define MAX_N 100010

signed main() {
    cin.tie(0); cout.tie(0);
    ios::sync_with_stdio(false);
    int A, B;
    cin >> A >> B;

    int n = 0;
    REP(i, 3) {
        n = A * n + B;
        if(n == 0) {
            printf("%lld\n", i + 1);
            return 0;
        }
    }
    printf("-1\n");

    return 0;
}