#include <iostream>
#include <iomanip>
#include <sstream>
#include <vector>
#include <string>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <functional>
#include <iterator>
#include <limits>
#include <numeric>
#include <utility>
#include <cmath>
#include <cassert>
#include <cstdio>

using namespace std; using namespace placeholders;

using LL = long long;
using ULL = unsigned long long;
using VI = vector< int >;
using VVI = vector< vector< int > >;
using VS = vector< string >;
using SS = stringstream;
using PII = pair< int, int >;
using VPII = vector< pair< int, int > >;
template < typename T = int > using VT = vector< T >;
template < typename T = int > using VVT = vector< vector< T > >;
template < typename T = int > using LIM = numeric_limits< T >;

template < typename T > inline istream& operator>>( istream &s, vector< T > &v ){ for ( T &t : v ) { s >> t; } return s; }
template < typename T > inline ostream& operator<<( ostream &s, const vector< T > &v ){ for ( int i = 0; i < int( v.size() ); ++i ){ s << ( " " + !i ) << v[i]; } return s; }
template < typename T > inline T fromString( const string &s ) { T res; istringstream iss( s ); iss >> res; return res; };
template < typename T > inline string toString( const T &a ) { ostringstream oss; oss << a; return oss.str(); };

#define REP2( i, n ) REP3( i, 0, n )
#define REP3( i, m, n ) for ( int i = ( int )( m ); i < ( int )( n ); ++i )
#define GET_REP( a, b, c, F, ... ) F
#define REP( ... ) GET_REP( __VA_ARGS__, REP3, REP2 )( __VA_ARGS__ )
#define FOR( e, c ) for ( auto &e : c )
#define ALL( c ) ( c ).begin(), ( c ).end()
#define AALL( a, t ) ( t* )a, ( t* )a + sizeof( a ) / sizeof( t )
#define DRANGE( c, p ) ( c ).begin(), ( c ).begin() + ( p ), ( c ).end()

#define SZ( v ) ( (int)( v ).size() )
#define PB push_back
#define EM emplace
#define EB emplace_back
#define BI back_inserter

#define EXIST( c, e ) ( ( c ).find( e ) != ( c ).end() )

#define MP make_pair
#define fst first
#define snd second

#define DUMP( x ) cerr << #x << " = " << ( x ) << endl

// 二部グラフ最大マッチング O( |V||E| )
class BipartiteMatching
{
private:
	const int V;
	vector< vector<int> > G;
	vector<int> match;
	vector<bool> used;

public:
	BipartiteMatching( int v ) : V( v ), G( V ), match( V, -1 ), used( V )
	{
		return;
	}

	void connect( int u, int v )
	{
		G[u].push_back( v );
		G[v].push_back( u );
		return;
	}

	int solve()
	{
		int res = 0;
		fill( match.begin(), match.end(), -1 );

		for ( int v = 0; v < V; ++v )
		{
			if ( match[v] == -1 )
			{
				fill( used.begin(), used.end(), false );
				if ( dfs( v ) )
				{
					res++;
				}
			}
		}

		return res;
	}

	VI restore() const
	{
		return match;
	}

private:
	int dfs( int v )
	{
		used[v] = true;

		for ( int i = 0; i < (int)G[v].size(); ++i )
		{
			int u = G[v][i], w = match[u];
			if ( w == -1 || ( !used[w] && dfs( w ) ) )
			{
				match[v] = u;
				match[u] = v;
				return true;
			}
		}

		return false;
	}
};
// BipartiteMatching( |V| )
// connect( u, v )
// solve()

int main()
{
	cin.tie( 0 );
	ios::sync_with_stdio( false );

	int N;
	cin >> N;

	VI A( N );
	cin >> A;

	BipartiteMatching bm( N * 2 );
	REP( i, N )
	{
		REP( j, N )
		{
			if ( A[i] != j )
			{
				bm.connect( N + i, j );
			}
		}
	}

	if ( bm.solve() < N )
	{
		cout << -1 << endl;
		return 0;
	}

	const VI res = bm.restore();
	copy_if( ALL( res ), ostream_iterator< int >( cout, "\n" ), bind( less< int >(), _1, N ) );
	cout << flush;

	return 0;
}