#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<vector>
#include<map>
#include<set>
#include<string>
#include<queue>
#include<stack>
using namespace std;
#define MOD 1000000007
#define INF (1<<29)
#define LINF (1LL<<60)
#define EPS (1e-10)
typedef long long Int;
typedef pair<Int, Int> P;

Int n, k, q;

int main(){
    cin >> q;
    for(int i = 0;i < q;i++){
        cin >> n >> k;
        if(k == 1)cout << n-1 << endl;
        else{
            Int floor = 1;
            Int now = 1;
            Int ans = 0;
            while(now < n){
                floor *= k;
                now += floor;
                ans++;
            }
            cout << ans << endl;
        }
    }
    return 0;
}