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

#define int long long

#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;

template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}


signed main(){
	int Q;cin>>Q;
	while(Q--){
		int N,K;
		cin>>N>>K;
		if(K==1){
			cout<<N-1<<endl;
			continue;
		}

		int sum=1;
		int p=1;
		for(int i=0;;i++){
			if(sum>=N){
				cout<<i<<endl;
				break;
			}
			p*=K;
			sum+=p;
		}
		
	}
	return 0;
}