#include<bits/stdc++.h>
#define pre val[(star[i]!=1)?star[i]-1:n]
#define nxt val[(star[i]!=n)?star[i]+1:1]
using namespace std;
int n,k,ans=0,sum=0,now=0;
bool vis[114514];
int val[114514],star[114514];
int main(){
	cin>>n>>k;
	for(int i=1;i<=n;i++) cin>>val[i],sum+=val[i];
	for(int i=1;i<=k;i++) cin>>star[i],vis[star[i]]=true;
	for(int i=1;i<=n;i++) ans+=val[i]*val[((i!=1)?i-1:n)];
	for(int i=1;i<=k;i++) now+=val[star[i]],ans+=val[star[i]]*(sum-now-((!vis[pre])?pre:0)-((!vis[nxt])?nxt:0));
	cout<<ans<<endl;
	return 0;
}