#include <iostream>
#include <vector>
#include <math.h>
using namespace std;
using ll = long long;
vector<int> ans;
int f(int n , int k){
	if(k == 1){
		return n - 1;
	}
	int now = 1 , res = 1;
	for(;res <= 1000; res++){
		if(res == 1)now += 1;
		if(res == 2)now += k;
		if(res >= 3)now+= pow(k , res - 1);
		if(now >= n)break;
	}
	return res;
}
int main(){
	int q;
	cin >> q;
	while(q--){
		int n , k;
		cin >> n >> k;
		ans.push_back(f(n , k));
	}
	for(int i = 0; i < ans.size(); i++){
		cout << ans[i] << endl;
	}
	return 0;
}