Codeforces_500_C

#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;

int vis[505],b[1005],w[505];
int main()
{
    int n,m,sum = 0;
    cin >> n >> m;
    for(int i = 1;i <= n;i++)
        cin >> w[i];
    for(int i = 1;i <= m;i++)
    {
        memset(vis,0,sizeof(vis));
        cin >> b[i];
        for(int j = i-1;j > 0;j--)
        {
            if(b[j] == b[i])
                break;
            if(!vis[b[j]])
            {
                sum += w[b[j]];
                vis[b[j]] = 1;
            }
        }
    }
    cout << sum << endl;
    return 0;
}