#include <stdio.h>
#include <string>
#include <cstring>
#include <stdlib.h>
#include <math.h>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <iterator>
#include <assert.h>
#pragma warning(disable:4996) 
 
typedef long long ll;
#define MIN(a, b) ((a)>(b)? (b): (a))
#define MAX(a, b) ((a)<(b)? (b): (a))
#define LINF 9223300000000000000
#define INF 2140000000
const long long MOD = 1000000007;
using namespace std;


int main(int argc, char* argv[])
{
    int Q;
    scanf("%d", &Q);
    int q;
    for(q=0; q<Q; q++) {
        int n,k;
        scanf("%d%d", &n, &k);

        if(k==1) {
            printf("%d\n", n-1); continue;
        }
        ll curr=1;
        int cnt=0;
        while(curr<n) {
            curr=curr*k+1;
            cnt++;
        }
        printf("%d\n", cnt);
    }

    return 0;
}