#include <bits/stdc++.h>
using namespace std;
int freq[(int)1e6];
int main() {
  int sz;
  cin >> sz;
  vector<int> free, numbers(sz);
  for (int i = 0; i < sz; i++) {
    cin >> numbers[i];
    freq[numbers[i]]++;
  }
  for (int i = 1; i <= sz; i++) {
    if (freq[i] == 0) {
      free.push_back(i);
    }
  }
  int pos = 0;
  for (int i = 0; i < sz; i++) {
    while (freq[numbers[i]] > 1 || numbers[i] > sz) {
      freq[numbers[i]]--;
      numbers[i] = free[pos];
      pos++;
    }
  }
  for (int i = 0; i < sz; i++) {
    cout << numbers[i] << " ";
  }
  cout << endl;
  return 0;
}
