#include <bits/stdc++.h>
using namespace std;
using i64 = long long;

int main() {
  i64 Q;
  cin >> Q;
  for(i64 i = 0;i < Q;i++) {
    i64 N, K;
    cin >> N >> K;
    i64 depth = 0;
    i64 now = 1;
    i64 cnt = 1;
    if(K == 1) {
      cout << N - 1 << endl;
      continue;
    }
    while(cnt < N) {
      now *= K;
      cnt += now;
      depth++;
    }
    cout << depth << endl;
  }
}