#[allow(unused)]
use proconio::{input, marker::Chars};

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