import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

Q = int(readline())
m = map(int,read().split())
NK = zip(m,m)

def solve(N,K):
    if K == 1:
        return N - 1
    dep = 0
    v = 1
    last_v = 1
    while True:
        if v >= N:
            return dep
        last_v *= K
        v += last_v
        dep += 1

# [solve(n,k) for n,k in [(4,2), (41,3), (100,1)]]

answer = [solve(n,k) for n,k in NK]
print('\n'.join(map(str,answer)))