#include<iostream>
#include<algorithm>
 
using namespace std;
 
int main(){
 
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        int *men = new int[n];
        int *women = new int[n];
 
        for(int i=0;i<n;++i){
            cin>>men[i];
        }
        sort(men, men+n);
        for(int j=0;j<n;++j){
            cin>>women[j];
        }
        sort(women, women+n);
        int prod = 0,ans = 0;
        for(int i=0;i<n;++i){
            prod = men[i]*women[i];
            ans += prod;
        }
        cout<<ans<<endl;
    }
    return 0;
 
}