use std::io::Read;

fn main() {
    let mut s = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: usize = itr.next().unwrap().parse().unwrap();
    let k: usize = itr.next().unwrap().parse().unwrap();
    let s: Vec<char> = itr.next().unwrap().chars().collect();

    let mut stack = Vec::new();
    for i in 0..n {
        if s[i] == '(' {
            stack.push(i);
        } else {
            let res = stack.pop().unwrap() + 1;
            if i + 1 == k {
                println!("{}", res);
                return;
            }
            if res == k {
                println!("{}", i + 1);
                return;
            }
        }
    }
}