from heapq import heappop, heappush
n, k, x = map(int, input().split())
a = list(map(int, input().split()))
ans = -10**10
h = []
t = 0
for i in range(n):
    heappush(h, a[i])
    t += a[i]
    if len(h) > k:
        t -= heappop(h)
    ans = max(ans, t - (i + 1) * x)
print(ans)