#include <bits/stdc++.h>
using namespace std;
int main(void){
    int n,k,x;
    cin>>n>>k>>x;
    long long sum=0,mx=-1e9;
    priority_queue<int>pq;
    for(int i=0;i<n;i++){
        int a;
        cin>>a;
        sum-=x;
        sum+=a;
        pq.push(-a);
        if(pq.size()>k){
            sum+=pq.top();
            pq.pop();
        }
        mx=max(mx,sum);
    }
    cout<<mx<<endl;
    return 0;
}