func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long t;     cin >> t;     while (t--) {       long long n;       cin >> n;       vector<long long> vis(n + 1, 0);       vector<long long> res(n);       vector<long long> v;       int b;       cin >> b;       v.push_back(b);       int cur = 1;       int ok = 1;       vis[v[0]] = 1;       res[0] = v[0];       for (int i = 1, a; i < n; i++) {         cin >> a;         v.push_back(a);         if (!ok) continue;         if (v[i] > v[i - 1]) {           vis[v[i]] = 1;           vis[v[i - 1]] = 1;           res[i] = v[i];           continue;         } else {           for (int j = cur; j < v[i]; j++) {             if (vis[j] == 0) {               vis[j] = 1;               res[i] = j;               cur = j + 1;               break;             }           }           if (res[i] == 0) {             ok = 0;           }         }       }       if (!ok)         cout << -1 << endl;       else {         for (int i = 0; i < res.size(); i++)           if (res[i] == 0)             cout << v[i] <<    ;           else             cout << res[i] <<    ;         cout << endl;       }     }   }   