Given an array of ~ N ~ positive integers ~ a_1, a_2, \ldots, a_N ~ and a positive integer ~ K ~. Select ~K ~ consecutive elements such that their sum is the largest. Print that value.

Input

• Line ~1~: Two positive integers ~ N ~ and ~ K ~ (~ K \leq N \leq 10^5 ~).
• Line ~2~: ~N ~ positive integers ~ a_1, a_2, \ldots, a_N ~ (~ a_i \leq 10^9 ~).

Output

• Print the value that satisfies the problem's requirement.

Sample Input

6 2
2 4 5 2 9 1 

Sample Output

11