#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)

int main()
{
    int n, k;
    ll x;
    cin >> n >> k >> x;
    vector<ll> a(n);
    rep(i, n) cin >> a[i];

    ll ans = LLONG_MIN / 2, sum = 0;
    priority_queue<ll, vector<ll>, greater<ll>> q;
    rep(i, n)
    {
        q.push(a[i]);
        sum += a[i];
        if (k < q.size())
        {
            sum -= q.top();
            q.pop();
        }
        if (ans < sum - x * (i + 1))
            ans = sum - x * (i + 1);
    }

    cout << ans << endl;
}