#include<bits/stdc++.h>
using namespace std;
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define rall(c) (c).rbegin(),(c).rend()
#define double long double
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll inf=1e9+7;
const ll mod=1e9+7;
ll gcd(ll a,ll b){
    if(min(a,b)==0)return max(a,b);
    if(max(a,b)%min(a,b)==0)return min(a,b);
    else return gcd(min(a,b),max(a,b)%min(a,b));
}
int main(){
    ll q;cin>>q;
    while(q){
        q--;
        ll n,k;cin>>n>>k;
        ll cnt=0;
        ll ans=-1;
        ll t=1;
        if(k==1)ans=n-1;
        else{
        while(cnt<n){
            cnt+=t;
            ans++;
            t*=k;
        }
        }
        cout<<ans<<'\n';
    }
}