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

void chmin(int64_t& a, int64_t b){
    a = min(a, b);
};

int main(){
    int Q;
    cin >> Q;
    while(Q--){
        int64_t A, B, C;
        cin >> A >> B >> C;
        if(C == 1){
            cout << -1 << endl;
            continue;
        }
        vector<int> nums;
        while(A){
            nums.push_back(A%C);
            A /= C;
        }
        reverse(nums.begin(), nums.end());
        int sz = nums.size();
        vector<int64_t> dp(sz+1, 1e9);
        dp[0] = 0;
        for(int i=0; i<sz; i++){
            chmin(dp[i+1], dp[i] + (i ? 1 : 0) + (nums[i] > 0));
            if(i < sz-1){
                int64_t V = nums[i] * C + nums[i+1];
                chmin(dp[i+2], dp[i] + (i ? 2 : 0) + (V+C-2)/(C-1));
            }
        }
        int64_t ans = dp[sz] * B;
        cout << ans << endl;
    }
    return 0;
}