# No.897 compαctree
q = int(input())
n = []
k = []

for i in range(q):
    tmp = [int(s) for s in input().split()]
    n.append(tmp[0])
    k.append(tmp[1])

for i in range(q):
    if k[i] == 1:
        print(n[i] - 1)
    else:
        depth = 1
        points = 1

        while points < n[i]:
            points += k[i] ** depth
            depth += 1

        print(depth - 1)