#include <bits/stdc++.h>
using namespace std;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
using Int = long long;
const char newl = '\n';

//INSERT ABOVE HERE
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);

  Int q;
  cin>>q;
  while(q--){
    Int n,k;
    cin>>n>>k;

    if(k==1){
      cout<<n-1<<endl;
      continue;
    }

    Int cnt=0,tmp=1,ans=0;
    while(n>cnt){
      cnt+=tmp;
      tmp*=k;
      ans++;
    }

    cout<<ans-1<<endl;
  }
  return 0;
}