r = lambda: map(int, raw_input().split())
n, m = r()
if m<2:
    print 0
    exit(0)
w = r()
INF = 10**9
def solve(b):
    global dp
    ret = -INF
    for i in xrange(1,n):
        base = b if i==n-1 else 0
        dp2 = [-INF] + [max(dp[j]+w[i-1]+base, rs[j]+base) for j in xrange(m)]
        for j in xrange(m+1):
            rs[j] = max(dp[j], rs[j])
        dp = dp2
        ret = max(ret, dp[m])
    return ret

dp = [-INF]*(m+1); rs = [-INF]*(m+1)
dp[1] = 0
rr = solve(w[-1])
dp = [-INF]*(m+1); rs = [-INF]*(m+1)
rs[0] = 0
print max(rr, solve(0))