from heapq import heappop, heappush

INF = 10**18

N, K, X = [int(s) for s in input().split()]
A = [int(s) for s in input().split()]

pq = []
sigma = 0

ans = -INF

for i, a in enumerate(A, start=1):
    heappush(pq, a)
    sigma += a

    if len(pq) > K:
        sigma -= heappop(pq)

    ans = max(ans, sigma - i * X)

print(ans)