#include <iostream>
#define int long long
using namespace std;

int q;
int n, k;

signed main() {
	cin >> q;
	for (int i = 0; i < q; i++) {
		cin >> n >> k;
		
		if (k == 1) { cout << n - 1 << endl; continue; }
		
		//1, k, k^2, … 和がn以上になればよい
		int s = 0, depth;
		int mul = 1;
		for (depth = 0; ; depth++) {
			s += mul;
			if (s >= n) break;
			mul *= k;
		}
		cout << depth << endl;
	}
	return 0;
}