#![allow(non_snake_case, unused_must_use, unused_imports)]
use std::io::{self, prelude::*};

fn main() {
    let (stdin, stdout) = (io::read_to_string(io::stdin()).unwrap(), io::stdout());
    let (mut stdin, mut buffer) = (stdin.split_whitespace(), io::BufWriter::new(stdout.lock()));
    macro_rules! input {
        ($t: ty, $n: expr) => {
            (0..$n).map(|_| input!($t)).collect::<Vec<_>>()
        };
        ($t: ty) => {
            stdin.next().unwrap().parse::<$t>().unwrap()
        };
    }

    let N = input!(usize);
    let A = input!(isize, N);

    let mut ans = isize::MIN;

    let mut min = 1 << 60;
    let mut max = -(1 << 60);

    for i in (0..N).rev() {
        ans = std::cmp::max(ans, -A[i]);

        let prev_min = min;
        let prev_max = max;

        min = std::cmp::min(-prev_max - A[i], prev_min);
        max = std::cmp::max(-prev_min - A[i], prev_max);

        min = std::cmp::min(min, -A[i]);
        max = std::cmp::max(max, -A[i]);

        ans = std::cmp::max(ans, max);
    }

    writeln!(buffer, "{}", ans);
}