#![allow(dead_code, unused_variables, unused_macros)]

fn main() {
    input!(n:usize, k:usize, s:String);
    let mut v = vec![0; n];
    let mut queue = vec![];
    s.chars().enumerate().for_each(|(i, c)| {
        if c == '(' {
            queue.push(i);
        } else {
            let o = queue.pop().unwrap();
            v[o] = i;
            v[i] = o;
        }
    });

    println!("{}", v[k - 1] + 1);
}

mod xxx {
    // https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
    #[macro_export]
    macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        input_inner!{$s, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}
    #[macro_export]
    macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

    #[macro_export]
    macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, bits)=>{
        u64::from_str_radix(&$next(), 2).expect("Parse error")
    };

    ($next:expr, hexs)=>{
        u64::from_str_radix(&$next(), 16).expect("Parse error")
    };


    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}
}