import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
class Fashion {
public static void main(String[] args) throws Exception{
Scanner s = new Scanner(System.in);
int t = s.nextInt();
while(t-- != 0)
System.out.println(calcHotness(s));
}
private static int calcHotness(Scanner s) throws Exception
{
int hot=0, N = s.nextInt();
ArrayList<Integer> men = readArray(N,s);
ArrayList<Integer> women = readArray(N,s);
Collections.sort(men);
Collections.sort(women);
for(int i=0;i<N;i++)
hot += men.get(i)*women.get(i);
return hot;
}
private static ArrayList<Integer> readArray(int N, Scanner s) throws java.lang.Exception{
ArrayList<Integer> a = new ArrayList<Integer>();
while(N-- != 0)
a.add(s.nextInt());
return a;
}
}
