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.*;
public class Main
{
	public static void main(String args[])throws IOException
	{
		InputReader reader =new InputReader(System.in);
		//PrintWriter ob=new PrintWriter(System.out);
				int n=reader.readInt();
				int ar[]=new int[n];
				int min=Integer.MAX_VALUE;
				for(int i=0;i<n;i++)
				{
					ar[i]=reader.readInt();
					if(ar[i]<=min)
					min=ar[i];
				}
				if(min==1)
				System.out.println("-1");
				else
				System.out.println("1");
		}
 static final class InputReader {
        private final InputStream stream;
        private final byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
 
        public InputReader(InputStream stream) {
            this.stream = stream;
        }
 
        private int read() throws IOException {
            if (curChar >= numChars) {
                curChar = 0;
                numChars = stream.read(buf);
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }
 
        public final int readInt() throws IOException {
            return (int)readLong();
        }
 
        public final long readLong() throws IOException {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
                if (c == -1) throw new IOException();
            }
            boolean negative = false;
            if (c == '-') {
                negative = true;
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return negative ? -res : res;
        }
 
        public final int[] readIntArray(int size) throws IOException {
            int[] array = new int[size];
            for (int i=0; i<size; i++) {
                array[i] = readInt();
            }
            return array;
        }
 
        public final long[] readLongArray(int size) throws IOException {
            long[] array = new long[size];
            for (int i=0; i<size; i++) {
                array[i] = readLong();
            }
            return array;
        }
 
        public final String readString() throws IOException {
            int c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.append((char)c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }
        private boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
    }
 
} 