import sys
import bisect

def main():
    N, K = map(int, sys.stdin.readline().split())
    A = list(map(int, sys.stdin.readline().split()))
    sumA = sum(A)
    if K == 0:
        print(0)
        return
    if K == 1:
        print(sumA)
        return

    B = A + A
    S = [0] * (2 * N + 1)
    for i in range(2 * N):
        S[i+1] = S[i] + B[i]

    low = 1
    high = sumA // K
    answer = 0

    MAX_LOG = 20

    while low <= high:
        mid = (low + high) // 2
        next_pos = [0] * (2 * N)
        for i in range(2 * N):
            target = S[i] + mid
            j = bisect.bisect_left(S, target, i+1, min(2*N+1, i + N +1))
            if j > 2 * N:
                j = 2 * N + 1  # unreachable
            next_pos[i] = j

        dp = [[0]*(2*N +2) for _ in range(MAX_LOG)]
        dp[0] = next_pos[:] + [2*N +1]*(2*N +2 - len(next_pos))

        for k in range(1, MAX_LOG):
            for i in range(2*N):
                if dp[k-1][i] >= 2*N:
                    dp[k][i] = 2*N +1
                else:
                    dp[k][i] = dp[k-1][dp[k-1][i]]

        ok = False
        for start in range(N):
            current = start
            cnt = 0
            end = start + N
            for k in reversed(range(MAX_LOG)):
                if current >= end:
                    break
                if dp[k][current] <= end:
                    cnt += (1 << k)
                    current = dp[k][current]
            if cnt >= K:
                ok = True
                break

        if ok:
            answer = mid
            low = mid + 1
        else:
            high = mid -1

    print(answer)

if __name__ == "__main__":
    main()