//#define _GLIBCXX_DEBUG
#include "bits/stdc++.h"

using namespace std;

//------------------------------- Libraries --------------------------------//

//------------------------------- Type Names -------------------------------//

using i64 = int_fast64_t;

using seika = string;
//akari : 1D, yukari : 2D, maki : 3D vector
template <class kizuna>
using akari = vector<kizuna>;
template <class yuzuki>
using yukari = akari<akari<yuzuki>>;
template <class tsurumaki>
using maki = akari<yukari<tsurumaki>>;
//akane : ascending order, aoi : decending order
template <class kotonoha>
using akane = priority_queue<kotonoha, akari<kotonoha>, greater<kotonoha>>;
template <class kotonoha>
using aoi = priority_queue<kotonoha>;

//------------------------------- Dubug Functions ---------------------------//
inline void print()
{
    cout << endl;
}
template <typename First, typename... Rest>
void print(const First &first, const Rest &... rest)
{
    cout << first << ' ';
    print(rest...);
}
//------------------------------- Solver ------------------------------------//

void solve()
{
    int q;
    cin >> q;
    while (q--)
    {
        i64 a, b, c;
        cin >> a >> b >> c;
        i64 ans = (a + c - 2) / (c - 1), t = 0;
        if (c == 1)
        {
            cout << -1 << endl;
            continue;
        }
        while (1)
        {
            if (a % c != 0)
            {
                t++;
            }
            a = (a - a % c) / c;
            if (a == 0)
            {
                break;
            }
            t++;
            for (i64 x = 1, y = 1; x <= a; x *= c, y++)
            {
                i64 d = a - x;
                ans = min(ans, t + (d + c - 2) / (c - 1) + y);
            }
            ans = min(ans, t + (a + c - 2) / (c - 1));
        }
        ans = min(ans, t);
        ans *= b;
        cout << ans << endl;
    }
}

int main()
{
    solve();
    return 0;
}