import sys

sys.setrecursionlimit(10 ** 6)
from bisect import *
from collections import *
from heapq import *

int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def SI(): return sys.stdin.readline()[:-1]
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
def MF(): return map(float, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LF(): return list(map(float, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
dij = [(0, 1), (1, 0), (0, -1), (-1, 0)]

def main():
    def imp():
        if ng[0]>=n:return False
        for i in range(n-1):
            if ng[i]!=ng[i+1]:return False
        return True

    def check():
        for i in range(n):
            if ans[i]==ng[i]:
                return i
        return -1

    n=II()
    ng=[II() for _ in range(n)]
    if imp():
        print(-1)
        exit()
    ans=list(range(n))
    while 1:
        i=check()
        if i==-1:break
        else:ans[i],ans[i-1]=ans[i-1],ans[i]
    print(*ans,sep="\n")

main()