use std::io::*;

fn main() {
  let s = stdin();
  let mut handle = s.lock();

  let mut buf = String::new();
  handle.read_line(&mut buf).ok();
  let l: Vec<u16> = buf
    .trim()
    .split_whitespace()
    .map(|e| e.parse().ok().unwrap())
    .collect();

  let k = l[1] - 1;
  let l = b'(';

  buf.clear();
  handle.read_line(&mut buf).ok();
  let s = buf.trim().as_bytes().to_vec();
  let mut b = Vec::new();
  for i in 0..s.len() {
    if s[i] == l {
      b.push(i);
    } else {
      let pop = b.pop().unwrap() as u16;
      if k == pop {
        println!("{}", i + 1);
        return;
      } else if k == i as u16 {
        println!("{}", pop + 1);
        return;
      }
    }
  }
}