import sys

# sys.setrecursionlimit(1000005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 63)
md = 10**9+7
# md = 998244353

from bisect import *

n, k = LI()
aa = LI()
cs = [0]
for a in aa*2: cs.append(cs[-1]+a)

def binary_search(l, r, minimize):
    if minimize: l -= 1
    else: r += 1
    while l+1 < r:
        m = (l+r)//2
        if ok(m) ^ minimize: l = m
        else: r = m
    if minimize: return r
    return l

def ok(m):
    l, r = 0, n
    i = 0
    for _ in range(k):
        j = bisect_left(cs, cs[i]+m)
        if j > n:
            i = j
            break
        if j-i < r-l: l, r = i, j
        i = j
    if i <= n: return True
    for si in range(l+1, r):
        i = si
        for _ in range(k):
            i = bisect_left(cs, cs[i]+m)
            if i > si+n: break
        if i <= si+n: return True
    return False

print(binary_search(1, sum(aa)//k, False))