fn is_kadomatsu((a, b, c): (isize, isize, isize)) -> bool {
    if a == b || b == c || c == a { return false; }
    (a.min(b).min(c) == b) || (a.max(b).max(c) == b)
}

fn solve() -> isize {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<isize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let mut result = 0isize;
    for start in 0..3 {
        let mut dp = vec![vec![0isize; 2]; n+1];
        for i in start..n+start-2 {
            let vals = (a[i], a[(i+1)%n], a[(i+2)%n]);
            dp[i][0] = if i == 0 { 0 } else if i < 3 { dp[i-1][0] } else { dp[i-1][0].max(dp[i-3][1]) };
            dp[i][1] = if i == 0 { 0 } else if i < 3 { dp[i-1][0] } else { dp[i-1][0].max(dp[i-3][1]) };
            dp[i][1] += if is_kadomatsu(vals) { a[i] } else { 0 };
        }
        result = result.max(dp.iter().map(|v| *v.iter().max().unwrap()).max().unwrap());
    }
    result
}

fn main() {
    let mut t = String::new();
    std::io::stdin().read_line(&mut t).ok();
    let t: usize = t.trim().parse().unwrap();
    let mut result = Vec::with_capacity(t);
    for _ in 0..t {
        result.push(solve());
    }
    for &v in result.iter() {
        println!("{}", v);
    }
}