import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = 10**16
# md = 998244353
md = 10**9+7

from functools import lru_cache

@lru_cache(None)
def cnt(a):
    if a < c: return 1
    if a <= 2*(c-1): return 2
    if a%c == 0: return cnt(a//c)+1
    return min(cnt(a//c), cnt(a//c+1))+2

for _ in range(II()):
    a, b, c = LI()
    if c==1:
        print(-1)
        continue
    ans = cnt(a)*b
    print(ans)
    cnt.cache_clear()