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
//560A : CURRENCY SYSTEM IN GERALDION

/*
 * Solution: 
 */

/*
 * Prerequisite:
 * 	- Logical thinking 
 */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;

//Your code goes here
public class Main {		
	static class ProblemSolver{
		public void solveTheProblem(InputReader in,PrintWriter out){
			int n=in.nextInt();
			boolean one=false;
			while(n-->0){
				int input=in.nextInt();
				if(input==1){
					one=true;
					break;
				}
			}
			if(one)System.out.println("-1");
			else System.out.println("1");			
		}					
	}
	
	//Default template for all the codes
	static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream),32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
	
	//Main method for all the codes
	public static void main(String[] args) {
		InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
		ProblemSolver problemSolver = new ProblemSolver();
		problemSolver.solveTheProblem(in, out);		
		out.close();		
	}

}
