#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
#define MOD ll(1e9+7)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cerr<<#x<<": "<<x<<endl


int main(){
    ll q;
    cin >> q;

    for(int i = 0; i < q; i++){
        ll n, k;
        cin >> n >> k;

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

        ll num = 1;
        ll ans = 0;
        ll c = 1;
        while(num < n){
            c *= k;
            num += c;
            ans++;
        }
        cout << ans << endl;
    }
    return 0;
}