#include <bits/stdc++.h>
using namespace std;

#define REP(i, m, n) for (int i = (m); i < (int)(n); i++)
#define REPS(i, m, n) for (int i = (m); i <= (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define reps(i, n) for (int i = 0; i <= (int)(n); i++)
#define rrep(i, x) for (int i = ((int)(x)-1); i >= 0; i--)
#define rreps(i, x) for (int i = (int)(x); i >= 0; i--)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb push_back
#define fi first
#define se second
typedef long long ll;
typedef pair<int, int> P;
const int inf = INT_MAX;
const ll INF = 1LL << 60;
const ll mod = 1e9 + 7;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) { fill( (T*)array, (T*)(array+N), val ); }

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int Q;
    cin >> Q;
    while(Q--) {
        ll A, B, C, D;
        cin >> A >> B >> C;

        if (C == 1) {
            cout << -1 << endl;
            continue;
        }

        vector<ll> bit;
        D = A;
        while (D > 0) {
            bit.pb(D%C);
            D /= C;
        }
        reverse(all(bit));

        int M = bit.size();
        vector<ll> sum(M+1), powC(M, 1), dp(M+1, A);

        REP(i, 1, M) {
            powC[i] = powC[i-1] * C;
        }
        REPS(i, 1, M) {
            rep(j, i) {
                sum[i] += bit[j] * powC[i-j-1];
            }
        }

        dp[0] = 0;
        rep(i, M) {
            if (sum[i] * C == sum[i+1]) {
                chmin(dp[i+1], dp[i] + 1);
            }
            if (sum[i] + C - 1 >= sum[i+1]) {
                chmin(dp[i+1], dp[i] + 1);
            }
            if (sum[i] * C + C - 1 >= sum[i+1]) {
                chmin(dp[i+1], dp[i] + 2);
            }
            if (i + 2 <= M && sum[i] + 2 * C - 2 >= sum[i+2]) {
                chmin(dp[i+2], dp[i] + 2);
            }
        }

        ll ans = dp[M] * B;
        cout << ans << endl;
    }
    return 0;
}