In a party of N people, each person is denoted by an integer. Couples are represented by the same number. Find out the only single person in the party of couples.

Example 1:

Input: N = 5
arr = {1, 2, 3, 2, 1}
Output: 3
Explaination: Only the number 3 is single.

Example 2:

Input: N = 11
arr = {1, 2, 3, 5, 3, 2, 1, 4, 5, 6, 6}
Output: 4
Explaination: 4 is the only single.

Your Task:
You do not need to read input or print anything. Your task is to complete the function findSingle() which takes the size of the array N and the array arr[] as input parameters and returns the only single person.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)

Constraints:
1 ≤ N ≤ 10⁴
1 ≤ arr[i] ≤ 10⁶