#include <bits/stdc++.h>
#include <atcoder/all>

using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)
template <class T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <class T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

void solve() {
	int n, k, x;
	cin >> n >> k >> x;
	vector<int> a(n);
	rep(i, 0, n) cin >> a[i];
	priority_queue<ll, vector<ll>, greater<ll>> pq;
	ll ans = -1e18;
	ll sm = 0;
	rep(i, 0, n) {
		sm += a[i];
		pq.push(a[i]);
		while ((int)pq.size() > k) {
			sm -= pq.top();
			pq.pop();
		}
		chmax(ans, sm - (i + 1) * x);
	}
	cout << ans << '\n';
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	int t = 1;
	// cin >> t;
	while (t--) solve();
}