import static java.lang.System.err;
import static java.lang.System.out;
import java.util.function.IntUnaryOperator;

public class Main {
	public static void main(String[] args) {
		new Main();
		out.flush();
		err.flush();
	}

	public Main() {
		try (java.util.Scanner sc = new java.util.Scanner(System.in)) {
			int N = sc.nextInt();
			final int MOD = 998_244_353;
			IntUnaryOperator pow2 = x -> {
				long ans = 1, mul = 2;
				while (x != 0) {
					if ((x & 1) != 0) ans = ans * mul % MOD;
					mul = mul * mul % MOD;
					x >>= 1;
				}
				return (int) ans;
			};
			long ans = 0;
			for (int i = 0; i < N; ++i) {
				long a = sc.nextInt();
				ans += a * pow2.applyAsInt(i) % MOD * (pow2.applyAsInt(N - i - 1) - 1) % MOD;
				ans -= a * (pow2.applyAsInt(i) - 1) % MOD * pow2.applyAsInt(N - i - 1) % MOD;
			}
			ans %= MOD;
			ans = (ans + MOD) % MOD;
			out.println(ans);
		}
	}
}