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

int main(){
  int n,k,x;
  cin>>n>>k>>x;
  vector<int> a(n);
  for (int i=0;i<n;i++) cin>>a[i];
  priority_queue<int> q;
  long long ans=0,ans2=-1e18;
  for (int i=0;i<n;i++){
    q.push(-a[i]);
    ans+=-a[i];
    if (q.size()==k+1){
      int t=q.top();q.pop();
      ans-=t;
    }
    ans2=max(ans2,-ans-1LL*x*(i+1));
  }
  cout<<ans2<<endl;
}