#include <bits/stdc++.h>   using namespace std;   int tab[205];   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     int t;     cin >> t;     while (t--) {       int n;       cin >> n;       vector<int> V;       for (int i = 0; i < n; i++) {         int x;         cin >> x;         tab[x] = 1;         V.push_back(x);       }       vector<int> V2;       bool b = 1;       for (int i : V) {         b = 0;         for (int j = i + 1; j <= 2 * n; j++) {           if (tab[j] == 0) {             tab[j] = 1;             b = 1;             V2.push_back(j);             break;           }         }         if (!b) {           break;         }       }       if (!b) {         cout <<  -1 n ;       } else {         for (int i = 0; i < n; i++) {           cout << min(V[i], V2[i]) <<     << max(V[i], V2[i]) <<    ;         }         cout <<   n ;       }       for (int i = 0; i <= 2 * n; i++) {         tab[i] = 0;       }     }   }   