#![allow(unused_imports)]

fn main() {
    input! {
        n: usize, k: usize, x: i64,
        a: [i64; n],
    }
    let mut que = BinaryHeap::new();
    let mut sum = 0;
    let mut ans = -1<<60;
    for a in a {
        sum += a;
        que.push(Reverse(a));
        if que.len() > k {
            let Reverse(b) = que.pop().unwrap();
            sum -= b;
        }
        sum -= x;
        chmax!(ans, sum);
    }
    println!("{ans}");
}

use proconio::{input, marker::*};
use itertools::{iproduct, izip, Itertools as _};
use std::{cmp::Reverse, collections::*};

#[macro_export]
macro_rules! chmax {
    ($a:expr, $b:expr) => {{
        let tmp = $b;
        if $a < tmp {
            $a = tmp;
            true
        } else {
            false
        }
    }};
}

#[macro_export]
macro_rules! chmin {
    ($a:expr, $b:expr) => {{
        let tmp = $b;
        if $a > tmp {
            $a = tmp;
            true
        } else {
            false
        }
    }};
}

#[macro_export]
/// mvec![]
macro_rules! mvec {
    ($val:expr; ()) => {
        $val
    };
    ($val:expr; ($size:expr $(,$rest:expr)*)) => {
        vec![mvec![$val; ($($rest),*)]; $size]
    };
}