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.text.DecimalFormat;
import java.util.*;

public class CF_560A {
	public static void main(String[] args) {
		new CF_560A().run();
	}
	public void run(){
		FastScanner sc = new FastScanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int n = sc.nextInt();

		boolean hasOne = false;
		for(int i = 0;i<n;i++){
			int tmp = sc.nextInt();
			if(tmp==1)
				hasOne = true;
		}
		if(hasOne)
			out.println(-1);
		else
			out.println(1);
		out.close();
	}
}
class FastScanner {
	public BufferedReader br;
	public StringTokenizer st;

	public FastScanner(InputStream in) {
		br = new BufferedReader(new InputStreamReader(in));
		st = null;
	}

	public boolean hasMoreTokens() {
		while (st == null || !st.hasMoreTokens()) {
			String line = null;
			try {
				line = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (line == null)
				return false;
			st = new StringTokenizer(line);
		}
		return true;
	}

	public String next() {
		if (!hasMoreTokens())
			return null;
		return st.nextToken();
	}

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

	public long nextLong() {
		return Long.parseLong(next());
	}

	//读一个int类型的数组
	public int[] readIntArray(int n) {
		int[] array = new int[n];
		for (int i = 0; i < n; i++) {
			array[i] = nextInt();
		}
		return array;
	}

	//读一个long数组
	public long[] readLongArray(int n) {
		long[] array = new long[n];
		for (int i = 0; i < n; i++) {
			array[i] = nextLong();
		}
		return array;
	}

	//读一个字符串数组
	public String[] readStringArray(int n) {
		String[] a = new String[n];
		for (int i = 0; i < n; i++) {
			a[i] = next();
		}
		return a;
	}

	//打乱一个数组，便于排序
	public void shuffleIntArray(int[] a) {
		Random rand = new Random();
		for (int i = 0; i < a.length; i++) {
			int x = rand.nextInt(i + 1); // 0~i
			int t = a[i];
			a[i] = a[x];
			a[x] = t;
		}
	}

	// 只适合比较小的数，太大的数会越界
	public long factorial(long n) {
		if (n == 0)
			return 1L;
		long res = 1;
		for (long i = 2; i <= n; i++) {
			res *= i;
		}
		return res;
	}

	// 只适合比较小的数，太大的数会越界
	public long combination(long mom, long son) {
		return factorial(mom) / (factorial(son) * factorial(mom - son));
	}

	//求最小公倍数
	public long gcd(long a, long b) {
		return b == 0 ? a : gcd(b, a % b);
	}

	//求最大公约数
	public long lcm(long a, long b) {
		return a * b / (gcd(a, b));
	}

	//格式化double类型的数
	public double format(String pattern, double d) {
		DecimalFormat df = new DecimalFormat(pattern);
		return Double.parseDouble(df.format(d));
	}

	//判断一个数是否是2的指数
	public boolean isPowerOfTwo(long v) {
		return (v & (v - 1)) == 0;
	}
}
