q = int(input())
for i in range(q):
    n, k = map(int, input().split())
    if k == 1:
        print(n - 1)
        continue
    sum, now, deaph = 1, 1, 0
    while sum < n:
        now *= k
        sum += now
        deaph += 1
    print(deaph)