#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;

#define pb push_back

const ld pi = 3.14159265358979323846;
const int mod = (int)1e9 + 7;
const ll INF = 1e18;

template<typename T>
T chmax(T a, T b) {
    return a > b ? a : b;
}

template<typename T>
T chmin(T a, T b) {
    return a > b ? b : a;
}

const int N = (int)1e5 + 1, M = N * 2;

void solve(){
    int n, l, r;
    cin >> n >> l >> r;

    int a[n];
    int f1 = 0, f2 = 0;
    for(int i = 0; i < n - 1; i++){
        cin >> a[i];
        if(a[i] == l) f1 = 1;
        if(a[i] == r) f2 = 1;
    }

    if(f1 && f2){
        for(int i = 1; i <= n; i++){
            cout << i << endl;
        }
    }
    else if(f1){
        cout << r << endl; 
    }
    else if(f2){
        cout << l << endl; 
    }
    else{
        cout << -1 << endl; 
    }
}

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

    int t = 1;
    // cin >> t; 

    while(t--){
        solve();
    }

    return 0;
}