import sys
sys.setrecursionlimit(2000)
input = sys.stdin.readline
#無限大
INF = (1 << 61) - 1
#4つのマスチェック用
four_step = [(0, 1), (1, 0), (-1, 0), (0, -1)]
def chmmin(a, b):
    if a > b:
        a = b
        return True
    else:
        return False
def chmax(a, b):
    if a < b:
        a = b
        return True
    else:
        return False
N, K, X = map(int, input().split())
array_A = list(map(int, input().split()))
from sortedcontainers import SortedList
S = SortedList()
do_count = 0
len_array_A = 0
last_ans = -1 * 10**10
for i in range(N):
    S.add(array_A[i])
    len_array_A += 1
    ans = 0
    do_count = min(K, i+1)
    #print("do_count", do_count)
    for j in range(do_count):
        if j < len_array_A:
            ans += S[len_array_A-1-j]
            #print("ans", ans)
        else:
            break
    #print(*S)
    #print(ans)
    ans -= X*(i+1)
    #print(ans)
    last_ans = max(ans, last_ans)
print(last_ans)