#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template<class T> using pqg = priority_queue<T, vector<T>, greater<T>>;

int main(){
    int N, K, X;
    cin >> N >> K >> X;
    vector<int> A(N);
    for (int& x : A) cin >> x;

    ll ans = LLONG_MIN, S = 0;
    pqg<int> Q;
    for (int i = 0; i < N; i++){
        Q.push(A[i]);
        S += A[i];
        if (Q.size() > K){
            S -= Q.top();
            Q.pop();
        }
        ans = max(ans, S-(ll)(i+1)*X);
    }

    cout << ans << endl;
}