Given non-zero two integers N and M. The problem is to find the number closest to N and divisible by M. If there are more than one such number, then output the one having maximum absolute value.

Example 1:
Input:
N = 13 , M = 4
Output:
12
Explanation:
12 is the Closest Number to
13 which is divisible by 4.
Example 2:
Input:
N = -15 , M = 6
Output:
-18
Explanation:
-12 and -18 are both similarly close to
-15 and divisible by 6. but -18 has
the maximum absolute value.
So, Output is -18

Your Task:
You don't need to read input or print anything. Your task is to complete the function closestNumber() which takes an Integer n as input and returns the answer.

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

Constraints:
-10^{5} <= N <= 10^{5}

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