from bisect import bisect_left, bisect_right
from itertools import accumulate
import sys


input = lambda: sys.stdin.readline().rstrip("\r\n")
INF = int(4e18)

if __name__ == "__main__":
    n, k = map(int, input().split())
    nums = list(map(int, input().split()))

    def check(mid: int) -> bool:
        max_ = bisect_right(preSum, mid)  # 第一段
        for start in range(max_):
            if start > n:
                break
            cur = start
            for _ in range(k):
                cur = bisect_left(preSum, preSum[cur] + mid, lo=cur)
                if cur > start + n:
                    break
            else:
                return True
        return False

    preSum = [0] + list(accumulate(nums + nums))
    left, right = 1, (sum(nums) // k) + 1
    while left <= right:
        mid = (left + right) // 2
        if check(mid):
            left = mid + 1
        else:
            right = mid - 1
    print(right)