using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int seitoCount = int.Parse(Reader.ReadLine());
        Dictionary<int, int> kirawareDic = new Dictionary<int, int>();
        int[] ans = new int[seitoCount];
        for(int i=0; i<ans.Length; i++) {
            ans[i] = -1;
        }
        bool canProc = true;
        Dictionary<int, int> input = new Dictionary<int, int>();

        List<int> numList = new List<int>();
        for(int i=0; i<seitoCount; i++) {
            int num = int.Parse(Reader.ReadLine());
            input.Add(i, num);
            if(num < seitoCount) {
                if(kirawareDic.ContainsKey(num)) {
                    kirawareDic[num]++;
                } else
                {
                    kirawareDic.Add(num, 1);
                }
            }
            numList.Add(i);
        }
        kirawareDic.OrderByDescending(a=>a.Value).ToList().ForEach((a)=>{
            List<int> target = new List<int>(input.Where(b=>b.Value != a.Key && ans[b.Key] < 0).Select(c=>c.Key));
            target.Sort((b, c)=>{
                bool bFlag = numList.Contains(input[b]);
                bool cFlag = numList.Contains(input[c]);
                if(bFlag && (!cFlag)) {
                    return -1;
                }
                if((!bFlag) && cFlag) {
                    return 1;
                }
                return 0;
            });
            if(target.Count > 0) {
                ans[target[0]] = a.Key;
                numList.Remove(a.Key);
            } else
            {
                canProc = false;
            }
        });
        if(numList.Count > 0 && canProc) {
            numList.ForEach((a)=>{
                for(int i=0; i<ans.Length; i++) {
                    if(ans[i] < 0) {
                        ans[i] = a;
                        break;
                    }
                }
            });
        }
        if(canProc) {
            ans.ToList().ForEach(a=>Console.WriteLine(a));
        } else
        {
            Console.WriteLine(-1);
        }
    }
    

    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"


5
1
1
1
0
1


 
";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
        public static int[] GetInt(char delimiter = ' ', bool trim = false)
        {
            string inptStr = ReadLine();
            if (trim)
            {
                inptStr = inptStr.Trim();
            }
            string[] inpt = inptStr.Split(delimiter);
            int[] ret = new int[inpt.Length];
            for (int i = 0; i < inpt.Length; i++)
            {
                ret[i] = int.Parse(inpt[i]);
            }
            return ret;
        }
    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}