Please subscribe to the official Codeforces channel in Telegram via the link ×

A. Currency System in Geraldion
time limit per test
2 seconds
memory limit per test
256 megabytes
standard input
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 minimum unfortunate sum?


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.


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

1 2 3 4 5