#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

/*================================*/

int Q, A, B, C;

int count(int a, int b, int c) {
    int cnt = 0;
    int remain = A;
    while(remain > c * 2 - 2) {
        if (remain % c > 0) {
            remain -= remain % c;
            cnt++;
        }
        remain /= c;
        cnt++;
    }
    
    // 少ない方
    if (remain < c) cnt += 1;
    else cnt += 2;
    
    return cnt * b;
}

signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin >> Q;
    
    REP(i, Q) {
        cin >> A >> B >> C;
        if (C == 1) {
            cout << -1 << endl;
        } else {
            cout << count(A, B, C) << endl;
        }
    }
    
    return 0;
}