#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int Q;
  cin>>Q;
  for(int i=0;i<Q;i++){
      int a,b;
      cin>>a>>b;
      if(b == 1){
          cout<<a-1<<endl;
          continue;
      }
      int now = b;
      int ans = 1;
      int sum = 1;
      while(sum < a){
          sum += now;
          ans++;
          now *= b;
      }
      cout<<ans-1<<endl;
  }
}