#include <bits/stdc++.h>
using namespace std;
int b[100001] = {}, c[100001] = {};
int main() {
  int n;
  while (cin >> n) {
    int a[n], x = 0;
    for (int i = 0; i < n; i++) {
      cin >> a[i];
      b[a[i]]++;
    }
    for (int i = 0; i < n; i++) {
      c[a[i]]++;
      if (c[a[i]] > 1 || a[i] > n) {
        while (1) {
          x++;
          if (b[x] == 0) {
            a[i] = x;
            break;
          }
        }
      }
    }
    for (int i = 0; i < n; i++) {
      cout << a[i] << " ";
    }
    cout << endl;
  }
}
