#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    ll q;
    cin >> q;
    rep(i, q) {
        ll n, k;
        cin >> n >> k;
        if (k == 1) {
            cout << (n - 1) << endl;
            continue;
        }
        ll cnt = 0, cur = 1, plus = 1;
        while(cur < n) {
            plus *= k;
            cur += plus;
            cnt++;
        }
        cout << cnt << endl;
    }
    return 0;
}