#include <iostream>
#include <vector>
#include <set>

using namespace std;

int main() {
    long long n, k, x;
    cin >> n >> k >> x;
    vector<long long> a(n);
    for (long long &l : a) {
        cin >> l;
    }

    set<long long> s;
    long long score = 0, ans = -1e18;
    for (int i = 0; i < n; i++) {
        s.insert(a[i]);
        score += a[i];
        score -= x;
        if (s.size() > k) {
            score -= *s.begin();
            s.erase(s.begin());
        }

        // cout << score << endl;

        ans = max(score, ans);
    }

    cout << ans << endl;
}