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
# -*- coding: utf-8 -*-
#ᕕ┌◕ᗜ◕┐ᕗ HELLO HELLO HELLO ᕕ┌◕ᗜ◕┐ᕗ

'''
INPUT:
Integer n, 1 <= n <= 1000
List l of integers a, 1 <= a <= 1,000,000
OUTPUT:
m, where m is the minimum positive integer that cannot be expressed as a sum of the elements of a
STRATEGY:
1. INPUT ALL DATA
1a. Input n
1b. Input all a into list l
2. DETERMINE MINIMUM SUM
2a. If 1 is in l, print -1. Otherwise, print 1
'''

#STEP 1: INPUT ALL DATA
n = int(raw_input())
l = list(int(i) for i in raw_input().strip().split(" "))
#STEP 2: DETERMINE MINIMUM SUM
if 1 in l:
    print -1
else:
    print 1
