#!/usr/bin/ python3.8
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
from collections import deque


class Dinic:
    def __init__(self, N, source, sink):
        self.N = N
        self.G = [[] for _ in range(N)]
        self.source = source
        self.sink = sink

    def add_edge(self, fr, to, cap):
        n1 = len(self.G[fr])
        n2 = len(self.G[to])
        self.G[fr].append([to, cap, n2])
        self.G[to].append([fr, 0, n1])  # 逆辺を cap 0 で追加

    def add_edge_undirected(self, fr, to, cap):
        n1 = len(self.G[fr])
        n2 = len(self.G[to])
        self.G[fr].append([to, cap, n2])
        self.G[to].append([fr, cap, n1])

    def bfs(self):
        level = [0] * self.N
        G = self.G
        source = self.source
        sink = self.sink
        q = deque([source])
        level[source] = 1
        pop = q.popleft
        append = q.append
        while q:
            v = pop()
            lv = level[v] + 1
            for to, cap, rev in G[v]:
                if not cap:
                    continue
                if level[to]:
                    continue
                level[to] = lv
                if to == sink:
                    self.level = level
                    return
                append(to)
        self.level = level

    def dfs(self):
        INF = 10**18
        G = self.G
        sink = self.sink
        prog = self.progress
        level = self.level
        ascend = False
        ff = 0
        stack = [(self.source, INF)]
        while stack:
            if ff:
                # このまま更新だけして戻っていく
                v, f = stack.pop()
                p = prog[v]
                to, cap, rev = G[v][p]
                G[v][p][1] -= ff
                G[to][rev][1] += ff
                continue
            v, f = stack[-1]
            if v == sink:
                ff = f
                stack.pop()
                continue
            E = G[v]
            lv = level[v]
            if ascend:
                # 流せずに戻ってきた
                prog[v] += 1
            find_flag = False
            for i in range(prog[v], len(E)):
                to, cap, rev = E[i]
                prog[v] = i
                if not cap:
                    continue
                if level[to] <= lv:
                    continue
                find_flag = True
                break
            if not find_flag:
                ascend = True
                stack.pop()
                continue
            ascend = False
            x = f if f < cap else cap
            stack.append((to, x))
        return ff

    def max_flow(self):
        flow = 0
        while True:
            self.bfs()
            if not self.level[self.sink]:
                return flow
            self.progress = [0] * self.N
            while True:
                f = self.dfs()
                if not f:
                    break
                flow += f
        return flow


N, *A = map(int, read().split())
source = N + N
sink = N + N + 1
dinic = Dinic(N + N + 2, source, sink)
for i, x in enumerate(A):
    for j in range(N):
        if j != x:
            dinic.add_edge(i, N + j, 1)

for i in range(N):
    dinic.add_edge(source, i, 1)
    dinic.add_edge(i + N, sink, 1)

f = dinic.max_flow()
if f < N:
    print(-1)
    exit()

for i in range(N):
    for to, cap, _ in dinic.G[i]:
        if cap == 0:
            print(to - N)