def solve(A, B, C):
    if C == 1: return -1
    res = 0
    while A > 2 * C - 2:
        A, mod = divmod(A, C)
        res += B
        if mod:
            res += B
    res += B if A < C else 2 * B
    return res


Q = int(input())
for _ in range(Q):
    print(solve(*map(int, input().split())))