#[allow(unused_imports)]
use std::{
    cell::RefCell, convert::{Infallible, TryFrom, TryInto as _},
    fmt::{self, Debug, Display, Formatter,}, fs::{File}, hash::{Hash, Hasher},
    iter::{Product, Sum}, marker::PhantomData,
    ops::{Add, AddAssign, Sub, SubAssign, Div, DivAssign, Mul, MulAssign, Neg, RangeBounds},
    str::{FromStr, SplitWhitespace}, sync::{atomic::{self, AtomicU32, AtomicU64}, Once},
    collections::{*, btree_map::Range}, mem::{swap},
    cmp::{self, Reverse, Ordering, Eq, PartialEq, PartialOrd},
    thread::LocalKey, f64::consts::PI, time::Instant, rc::Rc,
    ptr::null_mut,
    io::{self, stdin, Read, read_to_string, BufWriter, BufReader, stdout, Write},
};
#[allow(unused_imports)]
use proconio::{input, input_interactive, marker::{*}};
#[allow(unused_imports)]
//use rand::{thread_rng, Rng, seq::SliceRandom};
#[allow(unused_imports)]
//use ac_library::{*};

#[allow(dead_code)]
const INF: i64 = 1<<61;
#[allow(dead_code)]
const MOD: i64 = 998244353;
#[allow(dead_code)]
const D: [(usize, usize); 4] = [(1, 0), (0, 1), (!0, 0), (0, !0)];

pub fn floor(a:i64, b:i64)->i64{let res=(a%b+b)%b;(a-res)/b}
pub fn extended_gcd(a:i64,b:i64)->(i64,i64,i64)
{if b==0{(a,1,0)}else{let(g,x,y)=extended_gcd(b,a%b);(g,y,x-floor(a,b)*y)}}
pub fn mod_inverse(a:i64,m:i64)->i64{let(_,x,_) =extended_gcd(a,m);(x%m+m)%m}
pub fn comb(a: i64, b: i64, f: &Vec<(i64, i64)>)->i64{
    if a<b{return 0;}if b==0 || a==b{ return 1; }
    else{let x=f[a as usize].0;
        let y=f[(a-b) as usize].1;let z=f[b as usize].1;return((x*y)%MOD)*z%MOD;}}
pub fn factorial(x: i64)->Vec<(i64, i64)>{
    let mut f=vec![(1i64,1i64),(1, 1)];let mut z = 1i64;
    let mut inv = vec![0; x as usize+10];inv[1] = 1;
    for i in 2..x+1{z=(z*i)%MOD;
        let w=(MOD-inv[(MOD%i)as usize]*(MOD/i)%MOD)%MOD;
        inv[i as usize] = w;
        f.push((z, (f[i as usize-1].1*w)%MOD));}return f;}
pub fn fast_mod_pow(x: i64,p: usize, m: i64)->i64{
    let mut res=1;let mut t=x;let mut z=p;while z > 0{
        if z%2==1{res = (res*t)%m;}t = (t*t)%m;z /= 2; }res}

pub fn comb_vector(){

}
//use proconio::fastout;
//#[fastout]
fn main() {
    input! {
        n: usize,
        c: [i64; n],
    }
    let mut ans = 1;
    if c[0] < 0 && c[n-1] > 0{
        for &v in &c{
            if v != 0{
                ans = (ans*2)%MOD;
            } else {
                ans = (ans*3)%MOD;
            }
        }
        println!("{}", ans*mod_inverse(2, MOD)%MOD);
    } else {
        for _ in 0..n{
            ans = (ans<<1)%MOD;
        }
        println!("{}", ans*mod_inverse(2, MOD)%MOD);
    }
}