use std::collections::HashMap;

use proconio::input;

const MAX_RESULT: u64 = 1000000007;

fn calc_orders(ans: &[u64]) -> u64 {
    let mut visited_positions: HashMap<u64, usize> = HashMap::new();
    let mut result = 1;
    let l = ans.len();

    // For all reports, it needs to be at least 0 and at most n - 1.
    if l % 2 == 0 {
        for &a in ans.into_iter() {
            // In this case, all reports have to be odd and occur twice.
            // We don't have to check if a < 0 because a is unsigned and rust will panic during the
            // parsing of the input anyways.
            if a % 2 != 1 || a >= l as u64 {
                return 0;
            }

            let number_of_reports = *visited_positions.get(&a).unwrap_or(&0);
            if number_of_reports > 1 {
                return 0;
            } else if number_of_reports == 0 {
                result = (result * 2) % MAX_RESULT;
            }
            visited_positions.insert(a, number_of_reports + 1);
        }
    } else if l % 2 == 1 {
        // In this case, all reports have to be even, occur twice, except 0, which needs to occur
        // exactly once.
        for &a in ans.into_iter() {
            if a % 2 != 0 || a >= l as u64 {
                return 0;
            }

            let number_of_reports = *visited_positions.get(&a).unwrap_or(&0);
            if number_of_reports > 1 || (number_of_reports > 0 && a == 0) {
                return 0;
            } else if a != 0 && number_of_reports == 0 {
                result = (result * 2) % MAX_RESULT;
            }

            visited_positions.insert(a, number_of_reports + 1);
        }
    }

    return result;
}

fn main() {
    input! {
        n: usize,
        ans: [u64; n],
    };

    println!("{}", calc_orders(&ans));
}