func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   const int maxn = 2e5 + 5;   int a[maxn], lst[maxn];   bool used[maxn];   int occ[maxn];   int main() {     ios::sync_with_stdio(false);     int n;     cin >> n;     int ans = n;     for (int i = 1; i <= n; i++) {       cin >> a[i];       lst[a[i]] = i;       if (occ[a[i]] == 0) ans--;       occ[a[i]]++;     }     cout << ans <<   n ;     int j = 1;     for (int i = 1; i <= n; i++) {       if (!used[a[i]] && (a[i] < j || lst[a[i]] == i)) {         used[a[i]] = true;         cout << a[i] <<    ;       } else {         while ((j != a[i] && occ[j] > 0) || occ[j] == 1 || used[j]) j++;         used[j] = true;         cout << j <<    ;       }     }     cout <<   n ;     return 0;   }   