Q=int(input())
ans=[]
for i in range(Q):
    N,K=map(int,input().split())
    seg=0
    k_num=1
    while(N>k_num):
        k_num+=K
        K=K**(seg+1)
        seg+=1
    ans.append(seg)
for a in range(Q):
    print(ans[a])