50 50
75 71 23 37 28 23 69 75 5 62 3 11 96 100 13 50 57 51 8 90 4 6 84 27 11 89 95 81 10 62 48 52 69 87 97 95 30 74 21 42 36 64 31 80 81 50 56 53 33 99
26 30 5 33 35 29 6 15 36 17 32 16 14 1 29 34 22 40 12 42 38 48 39 50 13 47 18 43 10 8 49 45 11 31 21 37 46 28 20 41 2 7 9 24 27 23 3 44 15 14
 10 10
61 59 97 16 2 94 57 48 91 93
2 8 6 5 3 1 3 4 9 10
 2 1
1 2
1
 3 3
10 20 30
1 2 3
 50 60
86 57 45 93 17 12 40 10 47 80 18 80 3 9 6 55 13 99 5 76 4 70 100 55 27 91 71 3 65 93 41 74 80 56 90 50 58 13 71 9 47 52 26 73 72 21 15 81 88 28
40 32 5 16 49 23 3 17 14 10 1 15 1 21 28 22 13 45 12 25 44 48 46 32 36 43 11 8 49 7 7 35 10 14 39 4 42 10 30 27 1 17 31 15 8 41 44 33 25 26 19 18 29 37 50 6 36 38 47 9
 2 7
20 30
1 1 1 2 2 2 2
 2 2
10 12
2 1
 5 1
16 87 36 16 81
3
 2 3
20 30
1 1 1
 2 10
39 26
1 1 2 2 2 2 2 2 1 2

63929
 2137
 0
 40
 62514
 20
 12
 0
 0
 104

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;
 
/**
 * @author Don Li
 */
public class NewYearBookReading {
    void solve() {
        int n = in.nextInt(), m = in.nextInt();
        int[] w = new int[n];
        for (int i = 0; i < n; i++) w[i] = in.nextInt();
        int[] b = new int[m];
        for (int i = 0; i < m; i++) b[i] = in.nextInt() - 1;
 
        long ans = 0;
        boolean[] used = new boolean[n];
        for (int i = 0; i < n; i++) {
            Queue<Integer> qu = new LinkedList<>();
            for (int j = m - 1; j >= 0; j--) if (b[j] == i) qu.offer(j);
            int start = m - 1;
            while (!qu.isEmpty()) {
                int t = qu.poll();
                Arrays.fill(used, false);
                for (int k = start; k > t; k--) {
                    if (!used[b[k]]) {
                        used[b[k]] = true;
                        ans += w[i];
                    }
                }
                start = t - 1;
            }
        }
 
        out.println(ans);
    }
 
    public static void main(String[] args) {
        in = new FastScanner(new BufferedReader(new InputStreamReader(System.in)));
        out = new PrintWriter(System.out);
        new NewYearBookReading().solve();
        out.close();
    }
 
    static FastScanner in;
    static PrintWriter out;
 
    static class FastScanner {
        BufferedReader in;
        StringTokenizer st;
 
        public FastScanner(BufferedReader in) {
            this.in = in;
        }
 
        public String nextToken() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(in.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
 
        public int nextInt() {
            return Integer.parseInt(nextToken());
        }
 
        public long nextLong() {
            return Long.parseLong(nextToken());
        }
 
        public double nextDouble() {
            return Double.parseDouble(nextToken());
        }
    }
}
