#include <iostream>
#include <vector>
#include <unordered_map>
 
using namespace std;
 
int minCardsLeft(int n, int k, vector<int>& cards) {
    unordered_map<int, int> freq;
    for (int card : cards) {
        freq[card]++;
    }
 
    int minCards = 0;
    for (auto it = freq.begin(); it != freq.end(); ++it) {
        int num = it->first;
        int count = it->second;
        while (count >= k) {
            minCards += k;
            count -= (k - 1);
        }
        minCards += count;
    }
    return n - minCards;
}
 
int main() {
    int t;
    cin >> t;
 
    while (t--) {
        int n, k;
        cin >> n >> k;
        vector<int> cards(n);
        for (int i = 0; i < n; ++i) {
            cin >> cards[i];
        }
        cout << minCardsLeft(n, k, cards) << endl;
    }
 
    return 0;
}
 

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7
5 3
4 1 1 4 4
1 10
7
7 2
4 2 1 100 5 2 3
10 4
1 1 1 1 1 1 1 1 1 1
5 2
3 8 1 48 7
6 2
10 20 30 10 20 40
6 3
10 20 30 10 20 40