Second Largest Unique Number

Given a list of integers, your task is to find the second largest unique number in the list.

If the list contains fewer than two distinct numbers, output None.

For example, if the list is [4, 3, 1, 4, 2], the largest unique number is 4 and the second largest unique number is 3.

In mathematical notation, let \( S \) be the set of unique integers. If \( S = \{s_1, s_2, \ldots, s_k\} \) sorted in increasing order, you need to output \( s_{k-1} \). If \( |S| < 2 \), then output None.

inputFormat

The first line of input contains an integer n, representing the number of elements in the list. The second line contains n space-separated integers.

outputFormat

Output a single line containing the second largest unique number. If there is no such number, output None.

## sample

5
4 3 1 4 2

3

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