#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<stack>
#include<map>
#include<set>
#include<bitset>
#include<functional>
#include<assert.h>
#include<numeric>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
using ll = long long;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;
const ll mod=1e9+7 ;

int main(){
	int q;
	cin>>q;
	while(q--){
		ll n,k;
		cin>>n>>k;
		ll cur = 1;
		ll sum = 1;
		ll ans = 0;
		if(k==1){
			cout<<n-1<<endl;
			continue;
		}
		while(sum<n){
			++ans;
			cur*=k;
			sum+=cur;
		}
		cout<<ans<<endl;
	}
	return 0;
}