Currency System in Geraldion

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 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, ..., 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.

Sample test(s)

input

51 2 3 4 5

output

-1

地址：http://codeforces.com/contest/560/problem/A

思路：首先题目要看懂，于是就百度翻译了。　　　然后，本来以为是挺难的，考虑了下就两种情况，有1 没 1.   

#include <cstdio>

using namespace std;

int main(){

        int n;
        int ipt;
        while(scanf("%d", &n) != EOF){
                ;
                ; i < n; i ++){
                        scanf("%d", &ipt);
                         == ipt){
                                flag = ;
                                printf("-1\n");
                        }
                }
                 == flag){
                        printf("1\n");
                }
        }
        ;
}

ps: 个人总结，好久没A题，太懒了。好好加油，每天A一题，从今天开始希望能坚持。　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　2015-07-25 18:02:07