#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main(){
  ll n, k, x; cin >> n >> k >> x;
  vector<ll> a(n);
  for(ll i=0; i<n; i++) cin >> a[i];

  priority_queue<ll, vector<ll>, greater<ll>> pq;

  ll ans = -2147483647;
  ll csum = 0;
  for(ll i=0; i<n; i++){
    csum += a[i];
    pq.push(a[i]);

    while(pq.size() > k){
      csum -= pq.top();
      pq.pop(); 
    }
    ll f = csum - (x * (i+1));
    cerr << csum << " " << x*i << " " << f << endl;
    ans = max(ans, f);
  }

  cout << ans << endl;
}