Currency System in Geraldion

Currency System in Geraldion

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

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, ..., a_n (1 ≤ a_i ≤ 10⁶) — the values of the banknotes.

Output

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

Sample test(s)

Input

5
1 2 3 4 5

Output

-1
题意：给你某些数，经过任意加，是否可以组成任意数，是输出-1， 不是输出最小的不能组成的数，如果有1，经过任意加减肯定可以组成任意我们想要的数，如果没有1，那构不成的最小的数肯定是1啦

#include<iostream>
#include<cstdio>

using namespace std;

int main()
{
    int n, m, flag;

    while(scanf("%d", &n) != EOF)
    {
        flag = 0;

        while(n--)
        {
            scanf("%d", &m);

            if(m == 1)
                flag = 1;
        }
        if(flag)
            puts("-1");
        else
            puts("1");
    }
    return 0;
}