Scanf.scanf "%d %d %s" (fun n k s ->
    let a = Array.make n 0 in
    let lev = Array.make n 0 in
    let rec loop i level =
        if i < n then (
            if s.[i] = '(' then (
                lev.(level) <- i;
                loop (i + 1) (level + 1)
            ) else (
                let level = level - 1 in
                let cor = lev.(level) in
                a.(cor) <- i;
                a.(i) <- cor;
                loop (i + 1) level
            )
        )
    in
    loop 0 0;
    Printf.printf "%d\n" (a.(k - 1) + 1)
)