import sys
input = sys.stdin.readline

from heapq import heappop,heappush

N,K,X=list(map(int,input().split()))
A=list(map(int,input().split()))

H=[]
ANS=-1<<60
SUM=0

for i in range(N):
    a=A[i]
    heappush(H,a)
    SUM+=a

    while len(H)>K:
        x=heappop(H)
        SUM-=x

    ANS=max(ANS,SUM-(i+1)*X)

print(ANS)