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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
 
    long long N,K,X; cin >> N >> K >> X;
    priority_queue<long long,vector<long long>,greater<>> Q;
    long long sum = 0,answer = -1e18;
    for(int i=0; i<N; i++){
        long long a; cin >> a;
        Q.push(a),sum += a;
        if(Q.size() > K) sum -= Q.top(),Q.pop();
        answer = max(answer,sum-(i+1)*X);
    }
    cout << answer << "\n";
}