F. Owl Geeks

#include <bits/stdc++.h>

using namespace std;

#define cin_2d(vec, n, m) for(int i = 0; i < n; i++) for(int j = 0; j < m && cin >> vec[i][j]; j++);
#define cout_2d(vec, n, m) for(int i = 0; i < n; i++, cout << "\n") for(int j = 0; j < m && cout << vec[i][j] << " "; j++);
#define cout_map(mp) for(auto& [f, s] : mp) cout << f << "  " << s << "\n";
#define Time cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " Secs" << "\n";
#define fixed(n) fixed << setprecision(n)
#define ceil(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define fill(vec, value) memset(vec, value, sizeof(vec));
#define Num_of_Digits(n) ((int)log10(n) + 1)
#define mod_combine(a, b, m) (((a % m) * (b % m)) % m)
#define all(vec) vec.begin(), vec.end()
#define rall(vec) vec.rbegin(), vec.rend()
#define sz(x) int(x.size())
#define debug(x) cout << #x << ": " << (x) << "\n";
#define fi first
#define se second
#define Pair pair < int, int >
#define ll long long
#define ull unsigned long long
#define Mod  1'000'000'007
#define OO 2'000'000'000
#define EPS 1e-9
#define PI acos(-1)

template < typename T = int > istream& operator >> (istream &in, vector < T > &v) {
    for (auto &x: v) in >> x;
    return in;
}

template < typename T = int > ostream& operator << (ostream &out, const vector < T > &v) {
    for (const T &x: v) out << x << ' ';
    return out;
}

void AhMeD_HoSSaM(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
    #endif
}

void Solve(){
    ll a, b, n;
    cin >> a >> b >> n;
    vector < ll > points(10);
    for(ll i = 1; (a * i * i) + (b * i) <= n; i++){
        ll val = (a * i * i) + (b * i);
        vector < ll > freq(10);
        for(auto& d : to_string(val))
            freq[d - '0']++;
        ll max_freq = 0;
        for(auto& f : freq)
            max_freq = max(max_freq, f);
        for(int j = 0; j <= 9; j++)
            if(freq[j] == max_freq)
                points[j]++;
    }
    ll min_digit = 0, max_points = 0;
    for(int i = 0; i <= 9; i++)
        if(points[i] > max_points)
            max_points = points[i], min_digit = i;
    cout << (max_points == 0 ? -1 : min_digit) << '\n';
}

int main(){
    AhMeD_HoSSaM();
    int t = 1;
    cin >> t;
    while(t--)
        Solve();
    return 0;
}