#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;

#define pb push_back

const ld pi = 3.14159265358979323846;
// const int mod = 998244353;
const ll INF = 1e18;

template<typename T>
T chmax(T a, T b) {
    return a > b ? a : b;
}

template<typename T>
T chmin(T a, T b) {
    return a > b ? b : a;
}

const int N = (int)2e5 + 1, M = N * 2;

void solve(){
    ll n, d;
    cin >> n >> d;

    ld eps = 1e-18;
    if(logl(n) / log(d + 1) - (ll)(logl(n) / log(d + 1)) < eps){
        cout << logl(n) / log(d + 1) << endl;
    }
    else{
        cout << logl(n) / log(d + 1) + 1 << endl;
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int t = 1;
    cin >> t;

    while(t--){
        solve();
    }

    return 0;
}