n, m = map(int,input().split())
w = list(map(int, input().split())) + [0]
b = [(int(x)-1) for x in input().split()]
ans = 0
for i in range(m):
for j in range(i-1,-1,-1):
if b[j] == b[i]:
b[j] = n
break
ans += w[b[j]]
print(ans)#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define F first
#define S second
#define pb push_back
#define all(x) x.begin(), x.end()
const int maxn = 1e6 + 10;
const int MOD = 1e9+7;
int a[maxn], last[maxn], mark[maxn];
void solve(){
int n, m;
cin>> n>> m;
for(int i = 0; i < n; i++){
cin>> a[i + 1];
}
int x;
cin>> x;
vector<int>vec;
vec.pb(x);
for(int i = 1; i < m; i++){
cin>> x;
if(x != vec.back()) vec.pb(x);
}
int ans = 0;
int sum = 0;
int cnt = 1;
for(int u: vec){
//if(last[u]) cout<<"||||||||||"<< u<< endl;
int sum1 = 0;
fill(mark, mark + n + 1, 0);
for(int i = last[u]; i < cnt - 1; i++){
if(!mark[vec[i]]){
//if(!last[u]) cout<<a[vec[i]] <<" ";
sum1+= a[vec[i]];
mark[vec[i]] = 1;
}
}
//cout<< endl;
last[u] = cnt;
ans += sum1;
//cout<< sum1 << endl;
cnt++;
}
cout<< ans ;
}
int main(){
solve();
return 0;
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