fn is_kadomatsu(a: &Vec<isize>) -> bool {
    a[0] != a[1] && a[1] != a[2] && a[2] != a[0]
    && (*a.iter().max().unwrap() == a[1] || *a.iter().min().unwrap() == a[1])
}

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 1+start..=n+start-2 {
            let aval = a[(i-1) % n];
            dp[i][0] = dp[i-1][0];
            dp[i][1] = dp[i-1][0];
            dp[i][0] = dp[i][0].max(if i<3 { 0 } else { dp[i-3][1] });
            let vals = vec![aval, a[i % n], a[(i+1) % n]];
            dp[i][1] = dp[i][1].max(if i<3 { 0 } else { dp[i-3][1] }) + if is_kadomatsu(&vals) { aval } else { 0 };
        }
        result = result.max(*dp[n+start-2].iter().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);
    }
}