import sys
from collections import deque

def main():
    N, K, M = map(int, sys.stdin.readline().split())
    A = list(map(int, sys.stdin.readline().split()))
    S = [0] * (N + 1)
    for i in range(1, N+1):
        S[i] = S[i-1] + A[i-1]
    
    INF = -float('inf')
    dp = [ [INF]*(N+1) for _ in range(K+1) ]
    dp[0][0] = 0

    for j in range(1, K+1):
        dq1 = deque()  # Stores tuples of (i', value) where value is dp[j-1][i'] - S[i']
        dq2 = deque()  # Stores tuples of (i', value) where value is dp[j-1][i'] + S[i']
        for i in range(j, N+1):
            start_i = max(j-1, i - M)
            # Check if i-1 is a valid i' for the previous layer
            if i-1 >= 0 and dp[j-1][i-1] != INF:
                current_val1 = dp[j-1][i-1] - S[i-1]
                # Maintain deque1 in descending order
                while dq1 and dq1[-1][1] <= current_val1:
                    dq1.pop()
                dq1.append((i-1, current_val1))
                current_val2 = dp[j-1][i-1] + S[i-1]
                while dq2 and dq2[-1][1] <= current_val2:
                    dq2.pop()
                dq2.append((i-1, current_val2))
            
            # Remove elements from the front that are out of the window
            while dq1 and dq1[0][0] < start_i:
                dq1.popleft()
            while dq2 and dq2[0][0] < start_i:
                dq2.popleft()
            
            max_val1 = dq1[0][1] if dq1 else INF
            max_val2 = dq2[0][1] if dq2 else INF
            current_max = max(max_val1 + S[i], max_val2 - S[i])
            if current_max != INF:
                dp[j][i] = current_max
            else:
                dp[j][i] = INF
    
    print(dp[K][N])

if __name__ == '__main__':
    main()