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

int Q;
int N, K;

int main(){
	cin >> Q;
	for(int i = 0; i < Q; i++){
		cin >> N >> K;
		if(K ==  1){
			cout << N - 1 << endl;
			continue;
		}
		ll sum = 1;
		ll powK = 1;
		int res = 0;
		for(;;){
			if(sum >= N) break;
			powK *= K;
			sum += powK;
			res++;
		}
		cout << res << endl;
	}
	return 0;
}