#include <bits/stdc++.h>
using namespace std;
int a[100005];
int main() {
  int n;
  cin >> n;
  set<int> st;
  int x;
  for (int i = 1; i <= n; i++) {
    cin >> x;
    if (x >= 1 && x <= n) {
      if (st.count(x)) {
        a[i] = -1;
      } else {
        a[i] = x;
        st.insert(x);
      }
    } else
      a[i] = -1;
  }
  vector<int> v;
  for (int i = 1; i <= n; ++i) {
    if (!st.count(i)) v.push_back(i);
  }
  int j = 0;
  for (int i = 1; i <= n; ++i) {
    if (a[i] == -1) {
      a[i] = v[j];
      ++j;
    }
    cout << a[i] << " ";
  }
  return 0;
}
