题目链接：http://codeforces.com/problemset/problem/560/A
#include <iostream>
using namespace std;
int main()
{
int m,num,ans=1;
cin>>m;
for(int i=0; i<m; i++)
{
cin>>num;
if(num == 1)
ans=-1;
}
cout<<ans<<endl;
return 0;
}/*
Input
5
1 2 3 4 5
Output
-1
Answer
-1
*/
