func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long t;     cin >> t;     while (t--) {       long long n, k;       cin >> n >> k;       long long arr[n];       for (long long i = 0; i < n; i++) cin >> arr[i];       long long x = 0;       vector<long long> v;       map<long long, long long> mp;       for (long long i = 0; i < n; i++) {         if (mp.find(arr[i]) == mp.end()) {           v.push_back(arr[i]);           mp[arr[i]] = 1;           x++;         }       }       if (x > k)         cout << -1 << endl;       else {         long long x = 0;         while (v.size() < k) {           v.push_back(v[x]);           x++;         }         vector<long long> w;         long long j = 0, l = 0;         while (j < n) {           if (arr[j] == v[l]) {             w.push_back(arr[j]);             j++;             l++;           } else {             w.push_back(v[l]);             l++;           }           l %= v.size();         }         cout << w.size() << endl;         for (long long i = 0; i < w.size(); i++) cout << w[i] <<    ;         cout << endl;       }     }   }   