#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<map>
#include<set>
#include<cstdio>
#include<cmath>
#include<numeric>
#include<queue>
#include<stack>
#include<cstring>
#include<limits>
#include<functional>
#include<unordered_set>
#include<iomanip>
#include<cassert>
#define rep(i,a) for(int i=(int)0;i<(int)a;++i)
#define pb push_back
#define eb emplace_back
using ll=long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 50;
 
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
using namespace std;

template< typename T >
vector< T > convert_base(T x, T b) {
  vector< T > ret;
  T t = 1, k = abs(b);
  while(x) {
    ret.emplace_back((x * t) % k);
    if(ret.back() < 0) ret.back() += k;
    x -= ret.back() * t;
    x /= k;
    t *= b / k;
  }
  if(ret.empty()) ret.emplace_back(0);
  reverse(begin(ret), end(ret));
  return ret;
}

void solve(){
    int q;
    cin>>q;
    while(q--){
        ll a,b,c,ans=0;
        ll x=0,y=0;
        cin>>a>>b>>c;
        if(c==1){
            cout<<-1<<"\n";
            continue;
        }
        vector<ll>v=convert_base(a,c);
        ll n=v.size();
        if(n==1)ans=1;
        else {
            x=c*v.front()+v[1];
            x=(x+c-2)/(c-1);
            rep(i,2){
                if(v[i])y+=(2-i);
            }
            for(int i=2;i<n;++i)if(v[i])ans++;
            ans+=min(x,y)+(n-2);
        }
        cout<<ans*b<<"\n";
    }
}
 
 
signed main(){
	ios::sync_with_stdio(false);
        cin.tie(0);
	cout<<fixed<<setprecision(15);
	solve();
	return 0;
}