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

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>
#define LP pair<ll, ll>


int main() {
  int q;
  cin >> q;
  rep(qi,q) {
    ll n, k;
    cin >> n >> k;
    if (k == 1) {
      cout << n-1 << endl;
      continue;
    }
    ll ans = 0;
    ll tot = 1;
    ll now = k;
    while (tot < n) {
      tot += now;
      ans++;
      now *= k;
    }
    cout << ans << endl;


  }
  

  return 0;
}