#include <iostream>
#include<cstdio>
#include<set>
using namespace std;
int main() {
int t;
scanf("%d",&t);
while(t--) {
set <int> set1,set2;
int n;
scanf("%d",&n);
for(int i=0;i<n;i++) {
int temp;
scanf("%d",&temp);
set1.insert(temp);
}
for(int i=0;i<n;i++) {
int temp;
scanf("%d",&temp);
set2.insert(temp);
}
set <int>::iterator it2 = set2.begin();
for(set <int>::iterator it1 = set1.begin();it1!=set1.end() && it2!=set2.end();it1++,it2++) {
cout<<*it1<<" "<<*it2<<" ";
}
cout<<"\n";
}
return 0;
}
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