#![allow(
    non_snake_case,
    unused_variables,
    unused_assignments,
    unused_mut,
    unused_imports,
    unused_macros,
    dead_code,
    static_mut_refs
)]

// use ac_library::*;
use itertools::Itertools;
use proconio::{input, derive_readable,marker::*};
use std::{cmp::*, collections::*, dbg, fmt::*, hash::*, marker::PhantomData, ops::*, println};
// use rustc_hash::*;

fn main() {
    input!{
        n: usize,
        k: usize,
        x: isize,
        A: [isize;n],
    }
    const INF: isize = -3_000_000_000_000_000_000;

    let mut ans = INF;
    let mut hq = BinaryHeap::new();
    let mut now = 0;

    for a in A.iter().enumerate() {
        hq.push(-1*a.1);
        now += *a.1;
       

        if hq.len() > k {
            now -= -1*hq.peek().unwrap();
            hq.pop();
        }
        //  dbg!(&a,&hq,&now);
        ans = max(ans, now - x*(a.0 as isize +1));
    }

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

trait Pipe: Sized {
    fn pipe<F, T>(self, f: F) -> T
    where
        F: FnOnce(Self) -> T,
    {
        f(self)
    }
}
impl<T> Pipe for T {}

fn yesno(b: bool) {
    if b {
        println!("Yes");
    } else {
        println!("No");
    }
}