fun main() {
    val builder = StringBuilder()

    val q = readInputLine().toInt()

    // 有志解説を読んでもよくわからない……

    repeat(q) {
        val (a, b, c) = readInputLine().split(" ").map { it.toLong() }

        if (c == 1L) {
            builder.appendln(-1)
        } else {
            var tmp = a
            var cnt = 0L
            val ansCandidates = mutableSetOf<Long>()
            while (tmp != 0L) {
                if (tmp % c == 0L) {
                    tmp /= c
                } else {
                    ansCandidates.add(cnt + (tmp + c - 2L) / (c - 1L))
                    tmp = tmp / c * c
                }
                cnt++
            }
            ansCandidates.add(cnt)
            builder.appendln(ansCandidates.minOrNull()!! * b)
        }
    }

    print(builder.toString())
}

fun readInputLine(): String {
    return readLine()!!
}