#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
class solution
{
public:
void dot_product()
{
int n;
cin >> n;
vector<int> v1(n);
vector<int> v2(n);
for (int i = 0; i < n; i++) cin >> v1[i];
for (int i = 0; i < n; i++) cin >> v2[i];
sort(v1.begin(), v1.end());
sort(v2.begin(), v2.end(), greater<int>());
int sum = 0;
for (int i = 0; i < n; i++)
{
sum += (v1[i] * v2[i]);
}
cout << sum << "
";
}
};
int main()
{
solution ss;
int t;
cin >> t;
while (t--)
{
ss.dot_product();
}
return 0;
}