Maximum Height Difference in Consecutive Buildings

You are given a sequence of N building heights and an integer K. Your task is to find the maximum difference between the tallest and the shortest building in any group of K consecutive buildings.

In other words, for every contiguous subsequence of K buildings, compute the difference using the formula:

$$diff = \max_{i \le j \le i+K-1} H_j - \min_{i \le j \le i+K-1} H_j,$$

and output the maximum such difference among all valid groups.

Note: Input is provided via standard input and the answer must be printed to standard output.

inputFormat

The first line contains two integers N and K, where N is the number of buildings and K is the size of the consecutive group.

The second line contains N space-separated integers representing the heights of the buildings.

For example:

5 3
1 5 9 3 8

outputFormat

Output a single integer, which is the maximum difference between the tallest and the shortest building found in any contiguous group of K buildings.

For the sample input above, the output should be:

8

## sample

5 3
1 5 9 3 8

8

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