#include <bits/stdc++.h>
#define rep(i, n) for(int(i) = 0; (i) < (n); (i)++)
#define FOR(i, m, n) for(int(i) = (m); (i) < (n); (i)++)
#define ALL(v) (v).begin(), (v).end()
#define LLA(v) (v).rbegin(), (v).rend()
#define PB push_back
#define MP(a, b) make_pair((a), (b))
using namespace std;
template <class T> inline vector<T> make_vec(size_t a, T val) {
    return vector<T>(a, val);
}
template <class... Ts> inline auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec(ts...))>(a, make_vec(ts...));
}
template <typename T> inline T read() {
    T t;
    cin >> t;
    return t;
}
template <typename T> inline vector<T> readv(size_t sz) {
    vector<T> ret(sz);
    rep(i, sz) cin >> ret[i];
    return ret;
}
template <typename... Ts> inline tuple<Ts...> reads() {
    return {read<Ts>()...};
}
template <typename T> struct edge {
    int to;
    T cost;
    edge(int t, T c) : to(t), cost(c) {}
};
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using Graph = vector<vector<int>>;
template <typename T> using WGraph = vector<vector<edge<T>>>;
const int INF = 1 << 30;
const ll LINF = 1LL << 60;
const int MOD = 1e9 + 7;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int Q;
    cin >> Q;
    rep(i, Q) {
        auto [a, b, c] = reads<ll, ll, ll>();
        if(c == 1) {
            cout << -1 << endl;
            continue;
        }
        ll res = 0;
        ll div = 1;
        while(div * c <= a)
            div *= c;
        vector<ll> nums;
        while(a > 0) {
            nums.PB(a / div);
            a -= div * nums.back();
            div /= c;
        }
        for(int i = 0; i < nums.size();) {
            if(i == 0 && nums[i] * c + nums[i + 1] <= 2 * (c - 1)) {
                res += 3;
                i += 2;
            } else {
                if(nums[i])
                    res++;
                if(i != nums.size() - 1)
                    res++;
                i++;
            }
        }
        cout << res * b << endl;
    }
}