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

// package Codeforces;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Stack;
import java.util.StringTokenizer;

public class NewYearBookReading {
public static void main(String[] args) throws IOException{
	BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	StringTokenizer st= new StringTokenizer(in.readLine());
	int n = Integer.parseInt(st.nextToken());
	int m = Integer.parseInt(st.nextToken());
	int[] weights = new int[n];
	int [] readings = new int[m];;
	st = new StringTokenizer(in.readLine());
	for (int i = 0; i < weights.length; i++) {
		weights[i] = Integer.parseInt(st.nextToken());
	}
	st = new StringTokenizer(in.readLine());
	for (int i = 0; i < readings.length; i++) {
		readings[i] = Integer.parseInt(st.nextToken());
	}
	HashSet<Integer> order = new HashSet<Integer>();
	int [] ordered = new int[n];
	int count = 0;
	for (int i = 0; i < readings.length; i++) {
		if(!order.contains(readings[i])) {
			order.add(readings[i]);
			ordered[count++]=readings[i];
		}
	}
	Stack<Integer> stack = new Stack<Integer>();
	for (int i = ordered.length-1; i>=0; i--) {
		stack.push(ordered[i]);
	}
	Stack<Integer> tmp = new Stack<Integer>();
	long total = 0;
	for (int i = 0; i < readings.length; i++) {
		while(stack.peek()!=readings[i]) {
			tmp.push(stack.pop());
			total+=weights[tmp.peek()-1];
		}
		stack.pop();
//		System.out.println(tmp.toString());
		while(!tmp.isEmpty()) {
			stack.push(tmp.pop());
		}
//		System.out.println(readings[i]+" "+total);
		stack.push(readings[i]);
//		System.out.println(stack.toString());
	}
	System.out.println(total);
}
}
