#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int Q;
    cin >> Q;
    rep(loop, Q){
        ll n, k; cin >> n >> k;
        if(k == 1){
            cout << n - 1 << endl;
            continue;
        }
        int ans = 0;
        ll sum = 1;
        ll now = k;
        while(sum < n){
            sum += now;
            ans++;
            now *= k;
        }
        cout << ans << endl;
    }

   
    return 0;
}