#include <bits/stdc++.h>


using namespace std;
typedef long long ll;
#define REP(i,n) for(int i=0; i<int(n); i++)
#define FOR(i,m,n) for(int i=int(m); i<int(n); i++)
#define ALL(obj) (obj).begin(),(obj).end()
#define VI vector<int>
#define VLL vector<long long>
#define VVI vector<vector<int>>
#define VVLL vector<vector<long long>>
#define VC vector<char>
#define VS vector<string>
#define VVC vector<vector<char>>
#define VB vector<bool>
#define VVB vector<vector<bool>>
#define fore(i,a) for(auto &i:a)

typedef pair <int, int> P;
template<class T> bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }
const int  INF = 1 << 30;
const ll INFL = 1LL << 60;
const ll mod = 998244353;



int main() {
	
	int q;
	cin >> q;
	REP(i, q) {
		ll n, k;
		cin >> n >> k;
		ll m = k;
		if (k == 1) {
			cout << n - 1 << endl;
			continue;
		}
		int ans = 0;
		n--;
		while (true) {
			if (n <= 0)break;
			n -= k;
			k *= m;
			ans++;
		}
		
		cout << ans << endl;
	}
	
}