#include <bits/stdc++.h>
using namespace std;
using ui = unsigned int;
using ull = unsigned long long;
using ll = long long;
#define endl '\n'
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int maxn = 2e5 + 10;
const int mod = 1000000007;
#define inl inline
#define fr(i, a, b) for (int i = a; i <= b; i++)
#define ford(i, a, b) for (int i = a; i >= b; i--)
#define forall(i, a) for (auto &i : a)

/**
   ____         ___ _____
  / ___| _   _ / _ \___ /
  \___ \| | | | | | ||_ \
   ___) | |_| | |_| |__) |
  |____/ \__, |\___/____/
         |___/
*/
istream &operator>>(istream &in, vector<int> &v)
{
    for (auto &i : v)
        in >> i;
    return in;
}
ostream &operator<<(ostream &out, vector<int> &v)
{
    for (auto &i : v)
        out << i << " ";
    return out;
}
bool _output = 1;

#define int ll
void solve()
{
    int n, d;
    cin >> n >> d;
    using db = double;
    auto ans = log(n) / log(d + 1);
    int f_ans = (int)(ans);
    fr(i, f_ans - 1, f_ans + 1)
    {
        if (pow(d + 1, i) >= n)
        {
            cout << i << endl;
            return;
        }
    }
}

// 十字

// 4条
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int _ = 1;
    if (_output)
        cin >> _;
    while (_--)
        solve();
    return 0;
}