from collections import deque

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 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])