#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
#define DUMP(x) cout << #x << " = " << (x) << endl;
#define FOR(i, m, n) for (ll i = m; i < n; i++)
#define IFOR(i, m, n) for (ll i = n - 1; i >= m; i--)
#define REP(i, n) FOR(i, 0, n)
#define IREP(i, n) IFOR(i, 0, n)
#define FOREACH(x, a) for (auto&(x) : (a))
#define ALL(v) (v).begin(), (v).end()
#define SZ(x) ll(x.size())

void solve() {
  ll N, K;
  cin >> N >> K;
  // f(K,d)>=Nをみたす最小のd
  if (K == 1) {
    cout << N - 1 << endl;
    return;
  }
  ll d = ceil(log2(N * (K - 1) + 1) / log2(K)) - 1;
  cout << d << endl;
}

int main() {
  ll Q;
  cin >> Q;
  while (Q--) solve();
}