if __name__ == "__main__":
	Q = int(input())

	for _ in range(Q):
		n, k = map(int, input().split())

		if k == 1:
			print(n - 1)
		else:
			dep = 0
			now = 1
			tmp = 1
			while now < n:
				tmp *= k
				now += tmp
				dep += 1

			print(dep)