Minimum SubArray

You are given a sequence of n integers a1, a2, ..., an and an integer d. Find the length of the shortest non-empty contiguous subsequence with sum of elements at least d. Formally, you should find the smallest positive integer k with the following property: there is an integer s (1 ≤ s ≤ N-k+1) such that as + as+1 + ... + as+k-1 ≥ d. Input - The first line of the input contains a single integer