from bisect import bisect_left, bisect_right
from itertools import accumulate

n, k = map(int, input().split())
nums = list(map(int, input().split()))
preSum = [0] + list(accumulate(nums + nums))

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

l, r = 0, (sum(nums) // k) + 1
while l <= r:
    mid = (l + r) // 2
    if check(mid):
        l = mid + 1
    else:
        r = mid - 1
print(r)