from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right, insort
from itertools import permutations, combinations, groupby
from heapq import heappop, heappush
import math, sys
input = lambda: sys.stdin.readline().rstrip("\r\n")
def printl(li, sep=" "): print(sep.join(map(str, li)))
def yn(flag): print(Yes if flag else No)
_int = lambda x: int(x)-1
MOD = 998244353 #10**9+7
INF = 1<<60
Yes, No = "Yes", "No"

N, K, X = map(int, input().split())
s = 0
q = []
def add(x):
    global s
    heappush(q, x)
    s += x
    if len(q) > K:
        y = heappop(q)
        s -= y

A = list(map(int, input().split()))

ans = -INF
for i in range(N):
    add(A[i])
    ans = max(ans, s-(i+1)*X)
print(ans)