import numpy as np

N, M = map(int, input().split())
W = tuple(map(int, input().split()))
MAX = 1_000_000

if M < 2:
    print(0)
    exit()


def dp(last, non_last):
    for w in W[:-1]:
        new_last = np.full(M + 1, -MAX)
        new_last[1:] = np.maximum(last[:-1] + w, non_last[:-1])
        new_non_last = np.maximum(last, non_last)
        last, non_last = new_last, new_non_last
    return last, non_last


# dp[i] = iコの点を打ち終えている
# 一番目の点を含む
dp_last = np.full(M + 1, -MAX)
dp_non_last = np.full(M + 1, -MAX)
dp_last[1] = 0
dp_last, dp_non_last = dp(dp_last, dp_non_last)
ans = max(dp_last[-1] + W[-1], dp_non_last[-1])

# 一番目の点を含まない

dp_last = np.full(M + 1, -MAX)
dp_non_last = np.full(M + 1, -MAX)
dp_non_last[0] = 0
dp_last, dp_non_last = dp(dp_last, dp_non_last)
ans = max(ans, dp_last[-1], dp_non_last[-1])
print(ans)