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

    let mut bcnt = 0usize;
    let mut stack = vec![];
    for _ in 0..n {
        let val = s.pop().unwrap();
        if val == 'B' {
            stack.push(val);
            bcnt += 1;
        } else {
            if bcnt > 1 && stack[stack.len()-1] == 'B' && stack[stack.len()-2] == 'B' {
                stack.pop();
                bcnt -= 1;
            } else {
                stack.push(val);
            }
        }
    }
    let stack = stack.into_iter().rev().map(|c| c.to_string()).collect::<Vec<String>>();
    stack.join("")
}

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);
    }
}