Unique Element in List of Pairs

Given an array of integers nums of size n. Every element appears twice except for one. Return the element which appears only once.

Input Format

First Parameter - number n

Second Parameter - array of integers nums of size n

Output Format

Return the number.

Example 1

Input: 
    7
    2 5 1 9 2 9 5
Output:
    1

Example 2

Input:
    5
    1 6 6 8 1
Output:
    8

Constraints

• 0 < n < 10⁴
• 0 < arr[i] < 10⁵
• Expected Time Complexity: O(n)
• Expected Space Complexity: O(1)