A

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <iostream>
#include <list>
#include <climits>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <iomanip>

using namespace std;

#define REP(i,n) for(__typeof(n) i=0; i<(n); i++)
#define FOR(i,a,b) for(__typeof(b) i=(a); i<=(b); i++)
#define RFOR(i,a,b) for(__typeof(b) i=(a); i>(b); i--)
#define RESET(t,value) memset((t), value, sizeof(t))

#define READ(f) freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)

#define PI acos(-1.0)
#define INF (1<<30)
#define eps 1e-8
#define pb push_back
#define ppb pop_back
#define pii pair<int, int>

typedef long long int64;

#define Max 100000
vector <int64> adj[Max], result;
int64 color[Max];
set <int64> s;
int64 par[Max];
int64 d[Max],f[Max];
enum {white,grey,black };

void dfs_visit(int64 u) {
    color[u]=grey;
    for(int64 i=0; i<adj[u].size(); i++) {
        if(color[adj[u][i]]==white) {
            par[adj[u][i]]=u;
            dfs_visit(adj[u][i]);
        }
    }
    color[u]=black;
    result.pb(u);
}
void _reset() {
    REP(i, Max) adj[i].clear();
    memset(color,white,Max);
    memset(par,NULL,Max);
    s.clear();
    result.clear();
}
int main() {
    //READ("inputs.txt");
    int64 n, u, v, e;
    while(cin >> n) {
        _reset();
        e = n * 2;
        for(int64 i=0; i < e; i++) {
            cin>>u>>v;
            adj[u].pb(v);
            adj[v].pb(u);
            s.insert(u);
            s.insert(v);
        }
        dfs_visit(1);
        if(result.size() == n) {
            REP(i, result.size()) cout << result[i] << " ";
        } else cout << "-1";
        cout << "\n";
    }

    return 0;
}