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 n = l[0] as usize;
  let k = (l[1] - 1) as usize;
  let l = b'(';

  buf.clear();
  handle.read_line(&mut buf).ok();
  let mut v = Vec::with_capacity(n);
  let s = buf.trim().as_bytes().iter().enumerate().map(|e| {
    if e.1 == &l {
      v.push(e.0);
      None
    } else {
      let pop = v.pop().unwrap();
      if k == pop {
        Some(e.0 + 1)
      } else if k == e.0 {
        Some(pop + 1)
      } else {
        None
      }
    }
  }).find(|x| x.is_some());
  println!("{}",s.unwrap().unwrap());
}