A magic island Geraldion, where Gerald lives, has its own currency system. It uses banknotes of several values. But the problem is, the system is not perfect and sometimes it happens that Geraldionians cannot express a certain sum of money with any set of banknotes. Of course, they can use any number of banknotes of each value. Such sum is called unfortunate. Gerald wondered: what is the minimum unfortunate sum?

Input

The first line contains number n (1 ≤ n ≤ 1000) — the number of values of the banknotes that used in Geraldion. 

The second line contains n distinct space-separated numbers a1, a2, ..., an (1 ≤ ai ≤ 106) — the values of the banknotes.

Output

Print a single line — the minimum unfortunate sum. If there are no unfortunate sums, print  - 1.

Examples

Input

5
1 2 3 4 5


Output

-1
import java.io.*;
import java.util.StringTokenizer;


public class Main {
    final static boolean CONTEST = true;
    //region shit

    BufferedReader cin;
    PrintWriter cout;
    StringTokenizer stringTokenizer;
    StringTokenizer st;


    public static void main(String[] args) throws Exception {
        Main sol = new Main();
        if (CONTEST) {
            sol.cin = new BufferedReader(new InputStreamReader(System.in));
        } else {
            sol.cin = new BufferedReader(new FileReader("input.txt"));
        }
        sol.cout = new PrintWriter(System.out);
        sol.solve();
        sol.cin.close();
        sol.cout.close();
    }

    String nextToken() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(cin.readLine());
        }
        return st.nextToken();
    }

    int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    //endregion


    private void solve() throws Exception {
        int n = nextInt();
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < n; i++) {
            min = Math.min(min, nextInt());
        }
        cout.println(min == 1 ? -1 : 1);
    }
}
