#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
#include <map>
#include <queue>
#include <iomanip>
#include <set>
#include <tuple>
#define mkp make_pair
#define mkt make_tuple
#define rep(i,n) for(int i = 0; i < (n); ++i)
using namespace std;
typedef long long ll;
const ll MOD=1e9+7;

void solve(){
  ll N,K;
  cin>>N>>K;

  if(K==1){
    cout<<N-1<<endl;
    return;
  }

  ll sum=1;
  ll now=1;
  int ans=0;
  while(sum<N){
    now=now*K;
    sum+=now;
    ans++;
  }
  cout<<ans<<endl;
}

int main(){
  int Q;
  cin>>Q;
  rep(i,Q) solve();

  return 0;
}