import heapq
import sys

imput = sys.stdin.readline

n, k, x = map(int, input().split())
a = list(map(int, input().split()))

hq = []
top = 0
ans = -10 ** 18

for i in range(1, n + 1):
    t = a[i - 1]
    heapq.heappush(hq, t)
    top += t

    if len(hq) > k:
        removed = heapq.heappop(hq)
        top -= removed
    #print(hq)
    result = top - i * x
    if result > ans:
        ans = result

print(ans)