#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define ll long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define repl(i,a,b) for(ll i=(a);i<(b);i++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()

template <typename T> bool chmin(T &a,T b){if(a>b){a=b;return true;} return false;}
template <typename T> bool chmax(T &a,T b){if(a<b){a=b;return true;} return false;}


void solve(){
  int n,k,x; cin >> n >> k >> x;
  ll sum=0;
  ll ans=-1e18;
  priority_queue<int,vector<int>,greater<int>> que;
  rep(i,0,n){
    int a; cin >> a;
    if(que.size() == k){
      auto t=que.top(); que.pop();
      sum-=t;
      sum+=max(a,t);
      que.push(max(a,t));
    }
    else{
      sum+=a;
      que.push(a); 
    }
    chmax(ans,sum-(ll)x*(i+1));
    // cout << sum-(ll)x*(i+1) << "\n";
  }
  cout << ans << "\n";

  return;
}
  
int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int T=1;
  // cin >> T;
  rep(_,0,T){
    solve();
  }
}