#![allow(unused_mut)]
#![allow(non_snake_case)]
#![allow(unused_macros)]
#![allow(unused_variables)]
#![allow(unused_imports)]
#![allow(dead_code)]
// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

macro_rules! max {
    ($x: expr) => ($x);
    ($x: expr, $($y: expr),+) => {
        ::std::cmp::max($x, max!($($y),+))
    };
}

macro_rules! min {
    ($x: expr) => ($x);
    ($x: expr, $($y: expr),+) => {
        ::std::cmp::min($x, max!($($y),+))
    };
}

const MOD: usize = 1_000_000_007;
const MAX: usize = 510_000;
fn com_init(fac: &mut [usize], finv: &mut [usize], inv: &mut [usize]) {
    fac[0] = 1;
    fac[1] = 1;
    finv[0] = 1;
    finv[1] = 1;
    inv[1] = 1;
    for i in 2..MAX {
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

fn bin_coef(n: usize, k: usize, fac: &mut [usize], finv: &mut [usize], inv: &mut [usize]) -> usize {
    if k > n/2 {
        bin_coef(n-k, k, fac, finv, inv)
    } else {
        fac[n] * (finv[k] * finv[n - k] % MOD) % MOD
    }
}


use std::cmp;
use std::collections::{HashSet, BinaryHeap, VecDeque, HashMap};
use std::iter::FromIterator;
fn main() {
    input!{
        N: usize,
        K: usize,
        V: [isize; N],
    }

    let mut temochi = Vec::new();
    let mut max = 0;
    let toru = cmp::min(K, V.len());
    for kl in 0..toru+1 {
        for kr in 0..toru+1-kl {
            temochi.clear();
            temochi.extend_from_slice(&V[0..kl]);
            temochi.extend_from_slice(&V[(V.len()-kr)..V.len()]);
            temochi.sort();
            let modosu = cmp::min(K-kl-kr, kl+kr);
            let cand = temochi.iter().enumerate()
                            .skip_while(|&(ind, &val)| ind<modosu && val<0)
                            .fold(0isize, |acc, (ind, &val)| acc+val);
            max = cmp::max(max, cand);
        }
    }
    println!("{}", max);

}

Measured memory_bytes: 4352