#include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     int t;     cin >> t;     while (t--) {       int n;       cin >> n;       map<int, int> m;       bool f = true;       vector<int> v;       while (n--) {         int a;         cin >> a;         v.push_back(a);         m[a] += 1;         if (m[a] > 1) f = false;       }       if (!f || !m[1]) {         cout << -1 << endl;         continue;       }       vector<int> o;       set<int> s;       for (int a : v) {         o.push_back(a);         s.insert(a);         for (int i = a + 1; i < 201; i++)           if (!m[i] && s.find(i) == s.end()) {             o.push_back(i);             s.insert(i);             m[i] += 1;             break;           }       }       bool r = true;       int p;       for (int a : s) {         if (f) p = a, f = false;         if (a - p > 1) {           r = false;           break;         }         p = a;       }       f = false;       if (r)         for (int a : o) {           if (f) cout <<    ;           cout << a;           f = true;         }       else         cout << -1;       cout << endl;     }     return 0;   }   