#include <bits/stdc++.h>
#define int long long
#define pii pair<int,int>
//#define printf(...)
#define mp make_pair
using namespace std;
void solve()
{
    int n,d;
    cin>>n>>d;
    const int B = LLONG_MAX;
    function<int(int,int)> lift = [&] (int d, int k){
        if(k == 0) return 1LL;
        if(k==1) return d;
        int dd = lift(d, k/2LL);
        if(dd > B/dd) return LLONG_MAX;
        else dd = dd*dd;
        if(k&1LL){
            if(dd > B/d) return LLONG_MAX;
            else dd *= d;
        }
        return dd;
    };
    int L =1, R = 70;
    while(L<=R){
        int M = (L+R)/2LL;
        if(lift(d+1, M)>=n) R= M-1;
        else L = M+1;
    }
    cout<<L<<'\n';
}
signed main()
{
//    freopen("input_00.txt", "r", stdin);
    int T = 1;
    cin >> T;
    while(T--)
    {
        solve();
    }
}