#include <iostream>

using lint = long long;

void solve() {
    lint n, k;
    std::cin >> n >> k;

    if (k == 1) {
        std::cout << n - 1 << std::endl;
        return;
    }

    lint ch = 1, d = 0;
    while (true) {
        n -= ch;
        if (n <= 0) break;

        ch *= k;
        ++d;
    }

    std::cout << d << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    int q;
    std::cin >> q;
    while (q--) solve();

    return 0;
}