import heapq
import sys
from itertools import count

sys.setrecursionlimit(10 ** 6)
from typing import List, Tuple

int1 = lambda x: int(x) - 1
input = lambda: sys.stdin.readline().rstrip('\n')
ii = lambda: int(input())
vi = lambda: list(map(int, input().split()))
vi1 = lambda: list(map(int1, input().split()))


def dbg(*args, **kwargs):
    print(*(repr(arg) for arg in args), *(f'{k}: {repr(v)}' for k, v in kwargs.items()),
          sep='; ', file=sys.stderr, flush=True)


def main():
    n, k, x = vi()
    a = vi()
    h = []
    s = 0
    ans = -float('inf')
    for i in range(n):
        heapq.heappush(h, a[i])
        s += a[i]
        while len(h) > k:
            s -= heapq.heappop(h)
        s -= x
        ans = max(ans, s)
    return ans


def _start():
    if (ret := main()) is not None:
        print(*ret) if isinstance(ret, List) or isinstance(ret, Tuple) else print(ret)


if __name__ == '__main__':
    _start()