use proconio::input;
use std::collections::VecDeque;

fn main() {
    input! {
        _n: usize,
        s: String,
        r: i64,
        m: i64,
    }
    let a = s
        .chars()
        .map(|c| match c {
            '(' => 1,
            ')' => -1,
            _ => unreachable!(),
        })
        .collect::<Vec<_>>();
    let mut deque = VecDeque::<Event>::new();
    let mut start_value = 0;
    let mut end_value = 0;
    for (i, &x) in a.iter().enumerate() {
        end_value += x;
        while let Some(&Event { time: _, value }) = deque.front() {
            if end_value <= value {
                deque.pop_back();
            } else {
                break;
            }
        }
        deque.push_back(Event {
            time: i,
            value: end_value,
        });
    }
    let ans = if (end_value - start_value) % 2 == 0 {
        std::iter::once((start_value, deque.front().unwrap().value, end_value))
            .chain(a.iter().enumerate().map(|(i, &x)| {
                start_value += x;
                end_value += x;
                while let Some(&Event { time, value: _ }) = deque.front() {
                    if time < i {
                        deque.pop_front();
                    } else {
                        break;
                    }
                }
                while let Some(&Event { time: _, value }) = deque.front() {
                    if end_value <= value {
                        deque.pop_back();
                    } else {
                        break;
                    }
                }
                deque.push_back(Event {
                    time: s.len() + i,
                    value: end_value,
                });
                (start_value, deque.front().unwrap().value, end_value)
            }))
            .enumerate()
            .map(|(i, (x, y, z))| ((x - y + 1) / 2 + (z - y + 1) / 2) * m + i as i64 * r)
            .min()
            .unwrap()
    } else {
        -1
    };
    println!("{ans}");
}

#[derive(Debug, Clone, Copy)]
struct Event {
    time: usize,
    value: i64,
}