Currency system, international currency system

Currency system, international currency system

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 minimumunf Ortunate sum?

Input

The first line contains numberN(1 digit ≤ DigitNLimit ≤ limit 1000)-the number of values of the banknotes that used in Geraldion.

The second line containsNDistinct space-separated numbersA_{1, bytes,A2, middle..., middle ,...,AN(1 digit ≤ DigitAILimit ≤ limit 10^{6)-the values of the banknotes.}}

Output

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

Sample Input

Input

5 
1 2 3 4 5

Output

-1

Evaluate the minimum integer that n integers cannot constitute. If both exist, output-1.

Idea: If n has 1 in number, it can all be composed, and the output is-1. Otherwise, it cannot be composed of the smallest integer 1, and the output is 1.

I can't understand the meaning of this question .....

 

The Code is as follows:

 1 #include <iostream> 2 using namespace std; 3 int a[1005]; 4 int main() 5 { 6     int n; 7     while(cin>>n) 8     { 9         int flag=0;10         for(int i=0;i<n;i++)11         {12             cin>>a[i];13             if(a[i]==1)14                 flag=1;15         }16        17         if(flag)18             cout<<-1<<endl;19         else20             cout<<1<<endl;21     }22     return 0;23 }