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

int main() {
  ios::sync_with_stdio(false);

  int Q;
  cin >> Q;

  while (Q--) {
    int N, K;
    cin >> N >> K;

    if (K == 1) {
      cout << N - 1 << endl;
    } else {
      int64_t s = 0;
      int64_t pk = 1;
      for (int i = 0; ; ++i) {
        s += pk;
        pk *= K;
        if (s >= N) {
          cout << i << endl;
          break;
        }
      }
    }
  }

  return 0;
}