#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#define _USE_MATH_DEFINES
#include <cmath>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iostream>
#include <iomanip>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;

#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007; // 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};

struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    cerr << fixed << setprecision(10);
  }
} iosetup;
/*-------------------------------------------------*/
int main() {
  int q; cin >> q;
  while (q--) {
    long long a, b, c; cin >> a >> b >> c;
    if (c == 1) {
      cout << -1 << '\n';
      continue;
    }
    vector<long long> base;
    while (a > 0) {
      base.emplace_back(a % c);
      a /= c;
    }
    long long ans = LINF;
    while (base.size() >= 1) {
      long long tmp = base.size() - 1;
      for (long long e : base) {
        tmp += (e + c - 2) / (c - 1);
      }
      ans = min(ans, tmp);
      if (base.size() == 1) break;
      long long now = base.back() * c;
      base.pop_back();
      base.back() += now;
    }
    cout << b * ans << '\n';
  }
  return 0;
}