The Eco-Hiker

A hiker is planning a segment of a trail. Each mile has an elevation gain (positive integer). The hiker wants to find the SMALLEST continuous stretch of miles where the total elevation gain is at least K. However, the hiker refuses to traverse any mile that has an elevation gain strictly greater than a 'safety limit' S. If no such stretch exists, output -1. Example: Input: 6 15 10 5 8 12 4 6 7 Output: 3 Explanation: K=15, S=10. The mile with gain 12 is ignored. The stretch [4, 6, 7] sums to 17 (>= 15) and its length is 3.