class deque:
    def __init__(self):
        self.q = [None]*3005
        self.l = self.r = 0

    def __getitem__(self, item):
        if item == 0: return self.q[self.l]
        return self.q[self.r-1]

    def __len__(self):
        return self.r-self.l

    def append(self, x):
        self.q[self.r] = x
        self.r += 1

    def pop(self):
        self.r -= 1
        return self.q[self.r]

    def popleft(self):
        self.l += 1
        return self.q[self.l-1]

n, k, m = map(int, input().split())
a = list(map(int, input().split()))
s = [0]*(n+1)
for i in range(n): s[i+1] = s[i]+a[i]

def push(q, i, val):
    while len(q) and q[-1][-1] <= val: q.pop()
    q.append((i, val))

dp = [0]+[-1]*n
for _ in range(k):
    q1 = deque()
    q2 = deque()
    ndp = [-1]*(n+1)
    for i in range(n+1):
        if len(q1) and q1[0][0] < i-m: q1.popleft()
        if len(q2) and q2[0][0] < i-m: q2.popleft()
        if q1: ndp[i] = q1[0][1]+s[i]
        if q2: ndp[i] = max(ndp[i], q2[0][1]-s[i])
        if dp[i] != -1:
            push(q1, i, dp[i]-s[i])
            push(q2, i, dp[i]+s[i])
    dp = ndp

print(dp[-1])