#include "bits/stdc++.h"
#define REP(i, n) for(int i = 0; i < int(n); i++)
#define FOR(i,n,m) for(int i = int(n); i < int(m); i++)
using namespace std;
typedef long long ll;

//pow
template<typename T, typename U>
T pow(T k, U n, T unity = 1) {
    while (n > 0) {
        if (n & 1) {
            unity *= k;
        }
        k *= k;
        n >>= 1;
    }
    return unity;
}

int main() {
    int q; cin >> q;
    REP(i, q) {
        int n, k; cin >> n >> k;
        if (k == 1) {
            cout << n - 1 << endl;
            continue;
        }
        int ans = 0;
        ll sum = 0;
        while ((sum += pow((ll)k, ans, 1LL)) < n) {
            ans++;
        }
        cout << ans << endl;
    }
    return 0;
}