正整数

题目链接：http://acm.hust.edu.cn/vjudge/contest/view.action?cid=84077#problem/A

题目：

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


题意：问n个数所不能组成的最小的正整数是多少，如果都能组成输出-1

分析：有1输出-1，没有1输出1.

 1 #include<iostream>
 2 using namespace std;
 3 int a[1000];
 4 int main()
 5 {
 6 int t,i;
 7 cin>>t
 8 for(i=0;i<t;i++)
 9 cin>>a[i];
10 for(i=0;i<t;i++)
11  if(a[i]==1)
12  {cout<<-1<<endl;
13  break;}
14    if(i==t)
15        cout<<1<<endl;
16 return 0;
17 }