#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
// using namespace atcoder;
// using mint = modint1000000007;
// const int mod = 1000000007;
// using mint = modint998244353;
// const int mod = 998244353;
// const int INF = 1e9;
const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i, l, r) for (int i = (l); i < (r); ++i)
#define rrep(i, n) for (int i = (n)-1; i >= 0; --i)
#define rrep2(i, l, r) for (int i = (r)-1; i >= (l); --i)
#define all(x) (x).begin(), (x).end()
#define allR(x) (x).rbegin(), (x).rend()
#define P pair<int, int>
template<typename A, typename B> inline bool chmax(A& a, const B& b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A& a, const B& b) { if (a > b) { a = b; return true; } return false; }

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int n, k, x; cin >> n >> k >> x;
	long long ans = -LINF;
	using S = long long;
	std::priority_queue<S, std::vector<S>, std::greater<S>> pq;
	long long sum = 0;
	rep(i, n) {
		int a; cin >> a;
		sum += a;
		pq.push(a);
		if (pq.size() > k) {
			sum -= pq.top();
			pq.pop();
		}
		long long val = sum - (long long)x * (i + 1);
		chmax(ans, val);
	}
	cout << ans << endl;
	return 0;
}