n, k = map(int, input().split())
a = list(map(int, input().split()))

def is_possible(mid):
    current_sum = 0
    count = 0
    for num in a:
        current_sum += num
        if current_sum >= mid:
            count += 1
            current_sum = 0
    return count >= k

low = 0
high = sum(a)
answer = 0

while low <= high:
    mid = (low + high) // 2
    if mid == 0:
        if is_possible(1):
            low = mid + 1
        else:
            answer = 0
            break
    if is_possible(mid):
        answer = mid
        low = mid + 1
    else:
        high = mid - 1

print(answer)