#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep3(i, l, n) for (int i = l; i < (n); ++i)
#define sz(v) (int)v.size()
#define inf (int)(1e9+7)
template<typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { if (a < b) { a = b; return 1; } return 0; }
template<typename T> T gcd(T a, T b) { if (b == 0) return a; return gcd(b, a % b); }



// https://babcs2035.hateblo.jp/entry/2019/10/26/yukicoder%EF%BC%9ANo.915_Plus_Or_Multiple_Operation

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int q;
    cin >> q;
    while (q--) {
        int a, b, c;
        cin >> a >> b >> c;
        if (c == 1) { cout << -1 << endl; continue; }
        
        int cnt = 0, t = a; ll ans = 1e18;
        while (t) {
            if (t % c == 0) { t /= c; cnt++; }
            else {
                // 最後の方, 積より和のほうがいいことがある
                // 毎回確かめとく
                chmin(ans, cnt + (t + c - 2) / (c - 1));
                t -= t % c;
                ++cnt;
            }
        }
        chmin(ans, cnt);
        cout << (ll)ans * b << endl;
    }
    
}