#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using ll =  long long ;
using P = pair<int,int> ;
const int INF = 1e9;
const int MOD = 1000000007;

int main(){
    int q;
    cin >> q;
    rep(i,q){
        ll n,k;
        cin >> n >> k;
        if(k==1){
            cout << n-1 << endl;
            continue;
        }
        ll s = 0;
        ll a = 1;
        int cnt = 0;
        while(s < n){
            s += a;
            a *= k;
            cnt ++;
        }
        cout << cnt-1 << endl;
    }
    return 0;
}