import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		try (Scanner sc = new Scanner(System.in)) {
			int N = sc.nextInt();
			int[] B = new int[N];
			for (int i = 0;i < N;++ i) B[i] = sc.nextInt();
			final int MOD = 998_244_353;
			int use = -1, ans = 1, sum = 0;
			for (int i = 0;i < N;++ i) {
				if (B[i] == -1) {
					if (combination_mod2(N - 1, i) == 0) ans = ans * 2 % MOD;
					else ++ use;
				} else if (combination_mod2(N - 1, i) != 0) sum = sum + B[i] & 1;
			}
			if (use < 0 && sum == 0) System.out.println(0);
			else {
				while(use --> 0) ans = ans * 2 % MOD;
				System.out.println(ans);
			}
		}
	}
	
	static int combination_mod2(int n, int k) {
		return (n & k) == k ? 1 : 0;
	}
}