#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


# %%
Q = int(readline())
m = map(int, read().split())
ABC = zip(m, m, m)

# %%


def solve(A, C):
    if A < C:
        return 1
    if A < C + C - 1:
        return 2
    q, r = divmod(A, C)
    return solve(q, C) + 1 + (r > 0)


# %%
for a, b, c in ABC:
    if c == 1:
        print(-1)
    else:
        print(b * solve(a, c))