#include <stdio.h>
#define MOD 998244353

long long int power[200010],x[200010],y[200010];
int main()
{
	power[0] = 1;
	for(int i=1;i<=200000;i++) power[i] = (2*power[i-1])%MOD;
	
	int a;
	scanf("%d",&a);
	for(int i=1;i<=a;i++) scanf("%lld",&x[i]);
	for(int i=1;i<=a;i++)
	{
		y[i] = power[a-i] - power[i-1] + MOD;
		y[i] %= MOD;
	}
	long long int ans = 0;
	for(int i=1;i<=a;i++) ans += (y[i]*x[i]), ans %= MOD;
	printf("%lld",ans);
}