Segment Sum#2156
A segment of a sequence a_1, a_2, \ldots, a_N is a sequence a_i, a_{i+1}, \ldots, a_j for some 1 \leq i \leq j \leq N. Given an integer sequence, consider the set of all its segments, ordered by the sum of elements. Your task is to find the sum of elements of the -th segment in this order (-based). In this problem, two segments are considered different if one of their ends does not coincide. So, actually, it can be a multiset; for example, for the sequence , all its different segments are \{2\}, \{2\}, \{2, 2\}. Therefore, any sequence of length will have exactly N(N+1)/2 segments. For the given example, their sums will be in ascending order.
The first line of input contains two integer numbers and —the length of the sequence and the -based number of the interesting segment (1 \leq N \leq 10^5, 0 \leq K < N(N+1)/2). The second line contains integers a_1, a_2, \ldots, a_N—the elements of the sequence (-10^9 \leq a_i \leq 10^9).
Output the sum of elements of the -th segment in this order (-based).
Example 1