#include <iostream>
#include <set>
#include <utility>
#include <algorithm>
#define int ll
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int N=300*1000+10;
int t, it[N] , las[N] , n , k , a[N], c;
bool over(int a, int b){
	int tmp;
	return __builtin_mul_overflow(a, b, &tmp);
}
bool check(int ted){
	if(ted == 0)
		return true;
	fill(it , it+ted , -1);
	int cur=0 , ok=0;
	for(int i=0 ; i<n ; i++){
		if(ok == ted)
			return true;
		while(it[cur] >= k){
			cur = (cur+1)%ted;
		}
		if(it[cur] == -1){
                        las[cur] = a[i];
                        it[cur] ++;
                        if(it[cur] >= k)
				ok ++;
                        cur ++;
		}else if(!over(las[cur], c) && a[i] >= las[cur]*c){
			las[cur] = a[i];
			it[cur] ++;
			if(it[cur] >= k)
				ok ++;
			cur ++;
		}
		cur %= ted;
	}
	return (ok == ted);
}
void solve(){
        cin >> n >> k >> c;
	k--;
        for(int i=0 ; i<n ; i++)
                cin >> a[i];     
        sort(a , a+n);               
        int l=-1 , r=n+1;
        while(r-l>1){
		int mid = (l+r)/2;
		if(check(mid))
			l = mid;
		else
			r = mid;
        }
        cout << l << "\n";
}
int32_t main(){
	cin >> t;
	while(t--){
		solve();
	}
        return 0;
}