#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;

//template
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(a);i>(b);i--)
#define ALL(v) (v).begin(),(v).end()
typedef long long int ll; typedef pair<ll, ll> P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<typename A,size_t N,typename T>void Fill(A(&array)[N],const T &val){fill((T*)array, (T*)(array+N), val);}
const int inf = 0x3fffffff; const ll INF = 0x3fffffffffffffff;
//template end

void solve(){
    int a,b,c; scanf("%d%d%d",&a,&b,&c);
    if(c==1){
        printf("-1\n"); return;
    }
    ll ans=inf,cnt=0;
    while(a){
        chmin(ans,cnt+(a+c-2)/(c-1));
        if(a%c)a-=a%c; else a/=c; cnt++;
    }
    printf("%lld\n",ans*b);
}

int main(){
    int t; scanf("%d",&t);
    rep(rot,0,t)solve();
    return 0;
}