func_code_string: #include <bits/stdc++.h>   using namespace std;   signed main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     long long ct;     cin >> ct;     while (ct--) {       long long n, k;       cin >> n >> k;       vector<long long> a(n), was(n + 1), s;       long long tmp = 0;       for (long long i = 0; i < (n); ++i) {         cin >> a[i];         if (!was[a[i]]) {           tmp++;           was[a[i]]++;         }       }       if (tmp > k) {         cout <<  -1 n ;       } else {         for (long long i = 1; i < (n + 1); ++i) {           if (tmp < k and !was[i]) {             s.push_back(i);             tmp++;           }           if (was[i]) s.push_back(i);         }         cout << n * s.size() <<   n ;         for (long long i = 0; i < (n); ++i) {           for (long long j = 0; j < (s.size()); ++j) {             cout << s[j] <<    ;           }         }         cout <<   n ;       }     }   }   