import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

n=int(readline())
a=list(map(int, read().split()))
c=[0]*n
for x in a:
    if x<n:
        c[x]+=1
if n in c:
    print(-1)
    exit()
ans=[-1]*n
for _ in range(n):
    i=c.index(max(c))
    c[i]=-1
    for j, x in enumerate(a):
        if x!=i and ans[j]==-1:
            ans[j]=i
            c[x]-=1
            break
for x in ans:
    print(x)