import java.util.Arrays;
 
import java.io.*;
public class Main {
    public static void main (String[]args)throws Exception{
        BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
 
 
        int []A;int []B;
 
        int cases = Integer.parseInt(read.readLine());
        String[] men,finall,women;
        String result="";
 
 
        int couples,sum=0,a,b,positionA=0,positionB=0,i=0;
 
 
        for (i=0;i<cases;i++){
            couples = Integer.parseInt(read.readLine());
            A = new int [couples];
            B = new int [couples];
            men = read.readLine().split(" ");
            women = read.readLine().split(" ");
            for(int c=0;c<couples;c++){
                A[c]=Integer.parseInt(men[c]);
                B[c]=Integer.parseInt(women[c]);
            }
            Arrays.sort(A);
            Arrays.sort(B);
 
            for(int c=0;c<couples;c++){
                sum=sum + A[c]*B[c];
            }
            System.out.println(sum);
            sum = 0;
 
        }
    }
}
 

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3
2
1 1
3 2
3
2 3 2
1 3 2
20
4 5 3 6 8 9 4 5 3 2 1 9 0 8 7 10 8 7 3 2 
3 6 7 4 1 8 7 4 3 2 0 9 8 3 4 10 10 3 3 1