map<int, int>mpp;
int recurse(int n, int x, int anss = 0)
{

        string str = to_string(x);
        if ((int)str.size() == n)return anss;


        if (mpp.find(x) != mpp.end())return mpp[x];
        set<int>mp2;
        for0(i, (int)str.size())
        {
                mp2.insert(str[i] - '0');

        }
        int ans = 1e9;
        for (auto it : mp2)
        {
                if (it == 0 || it == 1)continue;
                ans = min(ans, recurse(n, x * it, anss + 1));
        }
        return mpp[x] = ans;

}
void solve()
{

        int n, x;
        cin >> n >> x;
        if (n == 1) {
                string str = to_string(x);
                if (str.size() > 1) {
                        int z = count(all(str), '0');
                        if (z) {cout << 1 << endl; return;}
                }


        }
        int ans = recurse(n, x);
        if (ans == 1e9) {cout << -1 << endl;}
        else cout << ans << endl;
        return;
}