/* -*- coding: utf-8 -*-
 *
 * 3656.cc:  No.3656 Game Scores and Costs - yukicoder
 */

#include<cstdio>
#include<set>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 200000;
const long long LINF = 1LL << 60;

/* typedef */

using ll = long long;
using msi = multiset<int>;

/* global variables */

int as[MAX_N];

/* subroutines */

/* main */

int main() {
  int n, k, x;
  scanf("%d%d%d", &n, &k, &x);
  for (int i = 0; i < n; i++) scanf("%d", as + i);

  ll sum = 0, maxf = -LINF;
  msi q;

  for (int i = 0; i < n; i++) {
    sum += as[i];
    q.insert(as[i]);
    while ((int)q.size() > k) sum -= *q.begin(), q.erase(q.begin());

    ll f = sum - (ll)x * (i + 1);
    maxf = max(maxf, f);
  }

  printf("%lld\n", maxf);
  
  return 0;
}