import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# md = 10**9+7
md = 998244353

from collections import deque

n,k,m=LI()
a=LI()
s=[0]*(n+1)
for i in range(n):s[i+1]=s[i]+a[i]

def push(q,i,val):
    while 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 q1 and q1[0][0]<i-m:q1.popleft()
        if 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])