Problem A CodeForces 560A

Description

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 minimumunfortunate 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 Input

Input

5
1 2 3 4 5

Output

-1
分析：
　　这题只用两种可能，就是输入有1与无1，有1时就找不到sum，所以输出-1；无1时有最小sum为1，即输出为1.

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
　　int n,i;
　　while(scanf("%d",&n)==1&&n)
　　{
　　　　int f=0;
　　　　for(i=0;i<n;i++)
　　　　{
　　　　　　int x;
　　　　　　scanf("%d",&x);
　　　　　　if(x==1)
　　　　　　f=1;
　　　　}
　　　　if(!f)
　　　　　　printf("1\n");
　　　　else
　　　　　　printf("-1\n");
　　}
return 0;
}