MOD = 10 ** 9 + 7
INF = 10 ** 10
import sys
sys.setrecursionlimit(100000000)
dy = (-1,0,1,0)
dx = (0,1,0,-1)
from collections import deque
from heapq import heapify,heappush,heappop

def dfs(x,c):
    if x == 0:
        return 0
    if 0 < x < c:
        return 1
    if c <= x < 2 * c - 1:
        return 2
    if x%c == 0:
        return dfs(x//c,c) + 1
    else:
        return dfs(x - x%c,c) + 1

def main():
    q = int(input())
    for _ in range(q):
        a,b,c = map(int,input().split())
        if c == 1:
            print(-1)
            continue

        ans = dfs(a,c)
        print(ans * b)
        
if __name__ =='__main__':
    main()