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

int main() {
    int Q;
    cin >> Q;
    while (Q--) {
        int N,K;
        cin >> N >> K;
        if(K == 1) {
            cout << N-K << endl;
        }
        else {
            long long ans = 0,sum = 1,tmp = 1;
            while (sum < N) {
                sum += tmp*K;
                ans++;
                tmp *= K;
            }
            cout << ans << endl;
        }
    }
}