#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

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