use std::collections::BTreeSet;

use proconio::input;

fn main() {
    // const D:usize=60;
    input! {
        t:usize,
    }

    for _ in 0..t {
        input! {
            n:usize,
            x:usize,
            c:[usize;n],
        }

        let mut xy = vec![];
        for i in 0..n {
            if x & (1 << c[i]) != 0 {
                continue;
            }

            let pow2 = 2usize.pow(c[i] as u32 + 1);
            let rem = x % pow2;
            let x = if x < pow2 { INF } else { rem + 1 };
            let y = pow2 / 2 - rem;
            xy.push((x, y));
        }
        if xy.is_empty() {
            println!("0");
            continue;
        }

        xy.sort_by(|a, b| b.0.cmp(&a.0));
        // println!("xy:{:?}",xy);
        let mut ans = INF;
        let mut bt = BTreeSet::new();
        for &(x, y) in xy.iter() {
            let maxy = *bt.iter().last().unwrap_or(&0);
            if x != INF {
                ans = ans.min(2 * (x + maxy));
            }
            bt.insert(y);
        }
        ans = ans.min(2 * *bt.iter().last().unwrap());

        println!("{}", ans);
    }
}
const INF: usize = std::usize::MAX;