#include <bits/stdc++.h>
using namespace std;
#define _ <<" "<<
#define sz(x) ((int) (x).size())
typedef pair<int, int> pii;
typedef long long ll;
#define debug(x) cout<<#x<<':'<<x<<endl;
typedef unsigned long long ull;
const int maxn=1000;
ll ksm(ll a,ll n){
    ll ans=1;
    while(n){
        if(n&1) ans=a*ans;
        a=a*a;
        n>>=1;
    }
    return ans;
}

int main(){
    int T;
    cin>>T;
    while(T--){
        ll n,d;
        cin>>n>>d;
        //debug(n);debug(d);
        //vector<ll> a(n+1);
        //a[0]=1;
        if(n==1){
            cout<<0<<endl;
            continue;
        }
        if(d>=n-1){
            cout<<1<<endl;
        }
        ll l=1,r=n;
        while(l<r){
            ll mid=(l+r)/2;
            if(ksm(d+1,mid)>=n){
                r=mid;
            }
            else l=mid+1;
        }
        cout<<l<<endl;
    }
}