#include <bits/stdc++.h>
using namespace std;

long depth(long n, long k) {
    if (k == 1) return n - 1;
    long s = 1, p = k, d = 0;
    while (s < n) {
        s += p;
        p *= k;
        d++;
    }
    return d;
}

int main() {
    long q;
    cin >> q;
    for (long i = 0; i < q; i++) {
        long n, k;
        cin >> n >> k;
        cout << depth(n, k) << endl;
    }
}