#include <bits/stdc++.h>

using namespace std;

using ll = long long;

ll solve(ll n, ll K) {
    if (K == 1) return n - 1;
    ll ans = 0;
    __int128_t hoge = K;
    while (true) {
        __int128_t foo = (hoge - 1) / (K - 1);
        if (foo >= n) {
            break;
        }
        ans++;
        hoge *= K;
    }
    return ans;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        ll n, K;
        cin >> n >> K;
        cout << solve(n, K) << "\n";
    }
    return 0;
}