#include <bits/stdc++.h>
using namespace std;

#define int long long

signed main(){
    int q;cin>>q;
    while(q--){
        int a,b;cin>>a>>b;
        if(b==1){
            cout<<a-1<<endl;
            continue;
        }
        int cnt=0,n=1,t=0;
        while(t<a){
            n*=b;cnt++;
            t+=n;
        }
        cout<<cnt<<endl;
    }
}