use std::io::*;
use std::str::FromStr;

#[allow(dead_code)]
fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

#[allow(dead_code)]
struct Main {}

#[allow(dead_code)]
impl Main {}

fn main() {
    let n = read::<usize>();
    let mut sushis = vec![0; n];
    for i in 0..n {
        sushis[i] = read::<i64>()
    }
    let mut p = 0;
    let mut q = 0;
    for i in 0..n {
        let new_p = q + sushis[i];
        q = if p > q { p } else { q };
        p = new_p;
    }
    println!("{}", if p > q { p } else { q });
}