Write a code to find the first non-repeating element in a given array arr of N integers. 

Note: Array consists of only positive and negative integers and not zero.

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Example 1: 

Input: arr [] = {-1, 2, -1, 3, 2} 

Output: 3 

Explanation: -1 and 2 are repeating whereas 3 is the only number occurring once. Hence, the output is 3.  

Example 2: 

Input: arr [] = {1, 1, 1} 

Output: 0

Note : (you can use any languages like JAVA, HTML/CSS/JS, Python, C/C++ or other)