We would like to request your feedback on the performance of AI assistant in response to the instruction and the given input displayed following.

Instruction: Write a function to find the maximum difference between two numbers in a given array.
Input: arr = [5, 3, 17, 11, 9]
Response: 
def max_difference(arr):
    max_diff = 0
    for i in range(len(arr)-1):
        diff = arr[i+1] + arr[i-1]
    return max_diff

Please rate according to the accuracy of the response to the instruction and the input. Each assistant receives a score on a scale of 0 to 5, where a higher score indicates higher level of the accuracy. Please first output a single line containing the value indicating the scores. In the subsequent line, please provide a comprehensive explanation of your evaluation, avoiding any potential bias. Please repeat the request first, then give your response.
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