import math

q = int(input())
for _ in range(q):
    a, b, c = map(int, input().split())
    if c == 1:
        print(-1)
        continue
    num = []
    while True:
        a, mod = divmod(a, c)
        num.append(mod)
        if a == 0:
            break
    # print(num)
    if len(num) == 1:
        print(b)
        continue
    ans = b * len(num) - b
    for i in range(len(num)):
        if num[i] != 0:
            ans += b
    if num[-1] == 1 and 0 < num[-2] < c-1:
        ans -= b
    # print(num)
    print(ans)