// yukicoder: No.897 compαctree
// 2019.10.5 bal4u

#include <stdio.h>

typedef long long ll;

int main()
{
	int N, K, Q, ans;
	ll k, s;

	scanf("%d", &Q); while (Q--) {
		scanf("%d%d", &N, &K);
		if (K == 1) ans = N-1;
		else {
			s = 1, k = 1, ans = 0;
			while (s < N) k *= K, s += k, ans++;
		}
		printf("%d\n", ans);
	}
	return 0;
}