Return the length of the shortest, non-empty, contiguoussubarray of A with sum at least K.

If there is no non-empty subarray with sum at least K, return -1.

Example 1:

Input: A = [1], K = 1
Output: 1

Example 2:

Input: A = [1,2], K = 4
Output: -1

Example 3:

Input: A = [2,-1,2], K = 3
Output: 3

Note:

1. 1 <= A.length <= 50000
2. -10 ^ 5<= A[i] <= 10 ^ 5
3. 1 <= K <= 10 ^ 9

见程序注释