#![allow(non_snake_case, unused_imports)]

use std::cmp::Reverse;
use std::collections::{BinaryHeap, HashMap, HashSet};
use proconio::{input, marker::Usize1, marker::Chars};
use itertools::Itertools;

#[allow(unused_macros)]
macro_rules! d {
    ( $( $x:expr ),* $(,)? ) => {
        eprintln!(
            concat!( $( stringify!($x), "={:?} " ),* ),
            $( $x ),*
        );
    };
}

#[allow(dead_code)]
fn yn(b: bool) -> &'static str {
    if b { "Yes" } else { "No" }
}

fn main() {
    input! {
        N: usize,
        K: usize,
        X: i64,
        A: [i64; N],
    }

    let mut q = BinaryHeap::<Reverse<i64>>::new();
    let mut tot = 0;
    let mut ans = i64::MIN;
    for (i, &a) in A.iter().enumerate() {
        q.push(Reverse(a));
        tot += a;
        if q.len() > K {
            if let Some(Reverse(x)) = q.pop() {
                tot -= x;
            }
        }
        
        let score = tot - X * (i+1) as i64;
        ans = ans.max(score);
    }

    println!("{}", ans);
}