import sys
import io, os
sys.setrecursionlimit(10**9)
input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline

q = int(input())
for _ in range(q):
    a, b, c = map(int, input().split())
    if c == 1:
        print(-1)
        continue
    memo = {}
    def dfs(x):
        if x == 0:
            return 0
        res = (x+c-2)//(c-1)
        if x == (x//c)*c:
            res = min(res, 1+dfs(x//c))
        else:
            res = min(res, 2+dfs(x//c))
        memo[x] = res
        return res
    ans = dfs(a)
    print(ans*b)