Longest Contiguous Subarray with Zero Sum

You are given an integer n and an array arr of n integers. Your task is to find the length of the longest contiguous subarray whose sum equals zero.

Example: For n = 8 and arr = [1, 2, -2, 4, -4, 2, -2, 1], the longest subarray with a zero sum is of length 6.

You need to read input from standard input (stdin) and output the result to standard output (stdout).

Hint: You might want to use a prefix sum array and a hash map to store the indices of the sums.

inputFormat

The first line of input contains a single integer n which denotes the number of elements in the array. The second line contains n space-separated integers representing the array arr.

For example:

8
1 2 -2 4 -4 2 -2 1

outputFormat

Output a single integer representing the length of the longest contiguous subarray with a sum of zero.

For the above example, the output should be:

6

## sample

8
1 2 -2 4 -4 2 -2 1

6

</p>