Codeforces Round #313 A. Currency System in Geraldion__codeforce

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 isn't 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 The sum is called unfortunate. Gerald Wondered:what is the minimum unfortunate sum?

Input

The 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 Input Input

5
1 2 3 4 5

Output

-1

The smallest integer that cannot be composed of n integers, if all exist, output-1.

Idea: If there are 1 of N, then all can be composed, output-1, otherwise can not be composed of the smallest integer digit 1, Output 1.

Code:

#include <cstdio>
using namespace std;
int a[1010];
int main ()
{
    int n,flag=0;
    while (scanf ("%d", &n)!=eof)
   {for

    (int i=0;i<n;i++)
    scanf ("%d", &a[i]);
    for (int i=0;i<n;i++)
    {
        if (a[i]==1)
        {
            flag=1;
            break;
        }
    }
    if (flag)
    printf (" -1\n");
    else
        printf ("1\n");

   }
    return 0;
}