#![allow(non_snake_case)]

use std::io::{ self, prelude::* };

macro_rules! pick {
    ($tokens:expr) => {
        $tokens.next().unwrap().parse().expect("parse error")
    }
}

fn main() {
    let mut s = String::new();
    io::stdin().read_to_string(&mut s).expect("i/o error");
    let mut tokens = s.split_whitespace();

    let _N: usize    = pick!(tokens);
    let mut K: usize = pick!(tokens); K -= 1;
    let S:  String   = pick!(tokens);
    let S:  Vec<_>   = S.chars().collect();

    let mut stk = vec![];
    let mut v   = [99999; 10000];
    for (i,&c) in S.iter().enumerate() {
        match c {
            '(' => {
                stk.push(i);
            },
            ')' => {
                let j = stk.pop().expect("stack underflow");
                v[i] = j;
                v[j] = i;
            },
            _ => panic!("unexpected char: {}", c),
        }
    }

    let ans = v[K] + 1;

    println!("{}", ans);
}