export function maxWindowSum(numbers: number[], k: number): number {
  if (numbers.length < k) return -1;
  let start = 0;
  let maxCount = -Infinity;
  let count = 0;

  for (let end = 0; end < numbers.length; end++) {
    count += numbers[end]

    if (end - start + 1 == k) {
      maxCount = Math.max(maxCount, count)
      count -= numbers[start]
      start++
    }
  }

  return maxCount;
}