Find the Unique Number

You are given an array of integers where every element appears exactly three times except for one unique element which appears only once. Your task is to find and print this unique element.

The solution should process the input read from standard input and output the answer to standard output.

Note: The approach is expected to run in linear time and constant extra space. A bit manipulation technique counting bit contributions is recommended.

inputFormat

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

outputFormat

Output a single integer which is the unique number appearing only once in the array.

## sample

4
2 2 3 2

3

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