#include <algorithm>
#include <array>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <optional>
#include <queue>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

int main() {
    int32_t q;
    cin >> q;
    for (auto i = 0; i < q; ++i) {
        int32_t n, k;
        cin >> n >> k;
        if (k == 1) {
            cout << n - 1 << endl;
            continue;
        }
        int64_t s = 1, t = 1, ans = 0;
        while (s < n) {
            ++ans;
            s += t * k;
            t *= k;
        }
        cout << ans << endl;
    }
    return 0;
}