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

int main() {
    int n, k, x;
    long long ans=-9999999999999999, f=0;
    cin >> n >> k >> x;
    vector<long long> a(n);
    priority_queue<long long, vector<long long>, greater<long long>> b;
    for(int i=0; i<n; i++) cin >> a.at(i);
    for(int i=0; i<n; i++) {
        b.push(a.at(i));
        f += a.at(i);
        if(k <= i) {
            f -= b.top();
            b.pop();
        }
        f -= x;
        ans = max(ans, f);
    }
    cout << ans;
}