q = int(input())

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

    def f(x):
        if x < c:
            return 1
        elif x - c + 1 < c:
            return f(x - c + 1) + 1
        elif x % c == 0:
            return f(x // c) + 1
        else:
            return f(x - x % c) + 1

    print(f(a) * b)