//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>
#include <locale>
#include <random>
#include <type_traits>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

using LL = long long;

//------------------------------------------
//------------------------------------------

typedef __int128 Lint;

Lint toLint(const string s) {
    Lint ret = 0;
    for (int i = 0; i < s.length(); i++)
        if ('0' <= s[i] && s[i] <= '9')
            ret = 10 * ret + s[i] - '0';
    return ret;
}

ostream &operator<<(ostream &dest, __int128_t value) {
    ostream::sentry s(dest);
    if (s) {
        __uint128_t tmp = value < 0 ? -value : value;
        char buffer[128];
        char *d = std::end(buffer);
        do {
            --d;
            *d = "0123456789"[tmp % 10];
            tmp /= 10;
        } while (tmp != 0);
        if (value < 0) {
            --d;
            *d = '-';
        }
        int len = std::end(buffer) - d;
        if (dest.rdbuf()->sputn(d, len) != len) {
            dest.setstate(ios_base::badbit);
        }
    }
    return dest;
}

istream &operator>>(istream &in, Lint &d) {
    string s;
    cin >> s;
    Lint tmp = 0;
    for (int i = 0; i < s.length(); i++)if ('0' <= s[i] && s[i] <= '9')tmp = 10 * tmp + s[i] - '0';
    d = tmp;
    return in;
}

int main() {

    LL Q;
    cin >> Q;

    while (Q--) {
        Lint N, K;
        cin >> N >> K;

        if (K == 1) {
            cout << N - 1 << endl;
            continue;
        }

        Lint d = 0;
        Lint sum = 1;
        Lint b = 1;
        while (sum < N) {
            d++;
            b *= K;
            sum += b;
        }
        cout << d << endl;
    }

    return 0;
}