52. Find the Unique Element

Difficulty: easy · Array, Bit Manipulation

Problem

You are given `N` integers in which exactly one value appears once and every other value appears exactly twice. Find the value that appears once.

Input

- Line 1: the integer `N` (always odd). - Line 2: `N` space-separated integers.

Output

Print the unique element.

Example 1

Input:
5
5 3 2 3 2
Output:
5

Explanation: 3 and 2 each appear twice; 5 appears once.

Example 2

Input:
1
42
Output:
42

Explanation: The only element is unique.

Constraints

- 1 <= N < 10^5, N odd - 0 <= each value <= 10^9

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