// #define STOPIT
#include <bits/stdc++.h>
#define loop(n) for (int ngtkana_is_genius = 0; ngtkana_is_genius < int(n); ngtkana_is_genius++)
#define rep(i, begin, end) for(int i = int(begin); i < int(end); i++)
#define all(v) v.begin(), v.end()
#define rand(l, r) std::uniform_int_distribution<>(l, r)(mt)
using lint = long long;
auto mt = std::mt19937_64(std::random_device{}());
auto cmn = [](auto& a, auto b){if (a > b) {a = b; return true;} return false;};
auto cmx = [](auto& a, auto b){if (a < b) {a = b; return true;} return false;};
void debug_impl() { std::cerr << std::endl; }
template <typename Head, typename... Tail>
void debug_impl(Head head, Tail... tail){
  std::cerr << " " << head;
  debug_impl(tail...);
}
#ifndef STOPIT
#define debug(...)\
  std::cerr << std::boolalpha << "[" << #__VA_ARGS__ << "]:";\
  debug_impl(__VA_ARGS__);\
  std::cerr << std::noboolalpha;
#else
#define debug 0;
#endif

template < typename Container, typename Value = typename Container::value_type, std::enable_if_t<!std::is_same< Container, std::string >::value, std::nullptr_t> = nullptr>
std::istream& operator>> (std::istream& is, Container& v)
  { for (auto & x : v) { is >> x; } return is; }

template < typename Container, typename Value = typename Container::value_type, std::enable_if_t<!std::is_same< Container, std::string >::value, std::nullptr_t> = nullptr >
std::ostream& operator<< (std::ostream& os, Container const& v) {
 os << "{";
  for (auto it = v.begin(); it != v.end(); it++)
    {os << (it != v.begin() ? "," : "") << *it;}
  return os << "}";
}

int main() {
  std::cin.tie(0); std::cin.sync_with_stdio(false);
  int q; std::cin >> q;
  loop(q) {
    int a, b, c;
    std::cin >> a >> b >> c;
    if (c == 1) {
      std::cout << -1 << std::endl;
      continue;
    }
    int now = 0;
    lint ret = std::numeric_limits< lint >::max();
    while (a) {
      int tmp = now + (a + c - 2) / (c - 1);
      // debug(a, now, tmp);
      cmn(ret, tmp);
      if (a % c) {
        a -= a % c;
      } else {
        a /= c;
      }
      now++;
    }
    int tmp = now + (a + c - 2) / (c - 1);
    // debug(a, now, tmp);
    cmn(ret, tmp);
    ret *= b;
    std::cout << ret << std::endl;
  }
  return 0;
}