import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


n,k = list(map(int, input().split()))
a = list(map(int, input().split()))
aa = a + a
s = sum(a)
def sub(x):
    if s<x*k:
        return False
    l = [None]*n
    v = a[0]
    j = 0
    for i in range(n):
        if j<i:
            j = i
            v = aa[i]
        while v<x:
            j += 1
            v += aa[j]
        l[i] = (j-i)+1
        v -= a[i]
    kk = 1
    dp = [l]
    while kk<n:
        tmp = [(dp[-1][i]+dp[-1][(dp[-1][i]+i)%n]) for i in range(n)]
        dp.append(tmp)
        kk *= 2
    vals = [0]*n
    index = list(range(n))
    for j in range(kk):
        if (k>>j)&1:
            for i in range(n):
                vals[i] += dp[j][index[i]]
                index[i] += dp[j][index[i]]
                index[i] %= n
#     print(l, dp, x)
    return any((vals[i]<=n) for i in range(n))
ll = 0
rr = s+1
while ll<rr-1:
    m = (ll+rr)//2
    if sub(m):
        ll = m
    else:
        rr = m
print(ll)