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

int main() {
  int n;
  cin>>n;
  for(int idx=0;idx<n;++idx){
    ll a,b;
    cin>>a>>b;
    ll cnt=0;
    ll sum=1;
    if(b==1){
      sum=a;
      cnt=a-1;
    }
    while(a>sum){
      ++cnt;
      sum+=pow(b,cnt);
    }
    cout<<cnt<<endl;
  }
}