Shortest Buffer Window

A data stream consists of a sequence of packet sizes. To process a batch, you need a contiguous subsequence of packets whose total size is at least K. Find the minimum number of packets required to reach this threshold. If no such window exists, return 0. Input Format: Line 1: An integer K representing the target sum. Line 2: A sequence of space-separated integers representing packet sizes. Output Format: A single integer representing the minimum length of the window. Example: Input: 25 10 2 3 15 20 1 Output: 2 (Explanation: The window [15, 20] has sum 35 >= 25 and length 2.)