#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char*mmap();
#define RD(v) int v=0;{int _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}

#define MD 998244353
#define MD2 ((1+MD)/2)
#define MD4 ((MD2+MD)/2)

main(){
	char*rp=mmap(0l,1l<<28,1,2,0,0ll);
	RD(n);
	long w=MD2;
	long x=1;
	long z=0;
	for(int i=0;i<n;++i){
		RD(a);
		z=(z+a*w)%MD;
		w+=MD4;
		w-=w<MD?0:MD;
		x+=x;
		x-=x<MD?0:MD;
	}
	printf("%d",z*x%MD);
}