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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, k, x;
    cin >> n >> k >> x;
    priority_queue<int, vector<int>, greater<int>> pq;
    ll sv = 0, ans = -(1ll << 60);
    for(int i = 0; i < n; i++){
        int v;
        cin >> v;
        sv += v;
        pq.emplace(v);
        if(pq.size() > k){
            sv -= pq.top();
            pq.pop();
        }
        ans = max(ans, sv - (ll)(i + 1) * x);
    }
    cout << ans << '\n';
}