#include <algorithm>
#include <vector>
#include <cfloat>
#include <string>
#include <cmath>
#include <set>
#include <cstdlib>
#include <map>
#include <ctime>
#include <iomanip>
#include <functional>
#include <deque>
#include <iostream>
#include <cstring>
#include <queue>
#include <cstdio>
#include <stack>
#include <climits>
#include <sys/time.h>
#include <cctype>

using namespace std;

typedef long long ll;

int main() {
  int n;
  scanf("%d", &n);
  int a[n];
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }

  bool check = false;
  for (int i = 0; i < n-1; i++) {
    if (a[i] != a[i+1]) {
      check = true;
      break;
    }
  }
  if (!check && a[0] < n) {
    puts("-1");
    return 0;
  }

  pair<int, int> memo[n];
  for (int i = 0; i < n; i++) {
    if (a[i] >= n) {
      memo[i] = {-1, i};
    }else {
      memo[i] = {a[i], i};
    }
  }
  sort(memo, memo+n);

  int ans[n];
  memset(ans, -1, sizeof(ans));
  for (int i = 0; i < n; i++) {
    if (memo[i].first != i) {
      bool ok = true;
      for (int j = i+1; j < n; j++) {
	if (memo[j].first == j) {
	  ok = false;
	  ans[memo[j].second] = i;
	  swap(memo[i], memo[j]);
	  break;
	}
      }
      if (ok) {
	ans[memo[i].second] = i;
      }
      continue;
    }
    for (int j = i+1; j < n; j++) {
      if (memo[j].first != i) {
	ans[memo[j].second] = i;
	swap(memo[i], memo[j]);
	break;
      }
    }
  }

  for (int i = 0; i < n; i++) {
    printf("%d\n", ans[i]);
  }

}