#include <bits/stdc++.h>

using namespace std;
typedef long long ll;


int main(){
    ll q, n, k, s;
    cin >> q;
    for (int i = 0; i< q; i++){
        cin >> n >> k;
        s = 0;
        if (k == 1)
            cout << n-1 << endl;
        else{
            for (int j = 0; j < 50; j++){
                s += pow(k, j);
                if (n <= s){
                    cout << j << endl;
                    break;
                }
            }
        }
    }
    
    return 0;

}