#include <bits/stdc++.h>
using namespace std::literals::string_literals;
using i64 = long long;
using std::cout;
using std::endl;
using std::cin;

template<typename T>
std::vector<T> make_v(size_t a){return std::vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return std::vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

int main() {
	int q; scanf("%d", &q);
	assert(1 <= q and q <= 10);
	
	while(q--) {
		int n, k; scanf("%d%d", &n, &k);
		assert(1 <= n and n <= (int)1e9);
		assert(1 <= k and k <= (int)1e9);
		
		if(k == 1) printf("%d\n", n - 1);
		else {
			int dep = 0;
			__int128 tmp = 1;
			const i64 T = (i64)n * (i64)(k - 1) + 1;
			while(tmp < T) {
				tmp *= (__int128)k;
				dep++;
			}
			printf("%d\n", dep - 1);
		}
	}
	return 0;
}

// Θ(ON)