#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
const long double PI = 4 * atan((long double)1);
const long long int INF = 1e18;
const long long int NINF = -1e18;
long long int get_hash(string s) {
  long long int N = 1000001;
  long long int base[N], A = 11, MD = 1110111110111;
  base[0] = 1;
  for (long long int i = (1); i < (N); ++i) base[i] = (base[i - 1] * A) % MD;
  long long int hs = 0;
  for (long long int i = (0); i < (s.size()); ++i) {
    hs += (s[i] * base[i]);
    hs %= MD;
  }
  return hs;
}
long long power(long long a, long long n) {
  long long res = 1;
  while (n) {
    if (n % 2) res *= a;
    a *= a;
    n /= 2;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n, m;
  cin >> n >> m;
  map<int, int> mpc;
  long long int a[n], b[m];
  for (long long int i = (0); i < (n); ++i) cin >> a[i];
  int arr[n];
  map<int, int> mpa, mpb;
  int k = 0;
  for (long long int i = (0); i < (m); ++i) {
    cin >> b[i];
    if (mpa[b[i]] != 1) {
      arr[k] = b[i];
      k++;
      mpa[b[i]] = 1;
    }
  }
  if (k != n) {
    for (long long int i = (1); i < (n + 1); ++i) {
      if (mpa[i] != 1) {
        mpa[i] = 1;
        arr[k] = i;
        k++;
      }
    }
  }
  stack<int> st, st1;
  for (int i = n - 1; i >= 0; i--) st.push(arr[i]);
  long long int ans = 0;
  for (long long int i = (0); i < (m); ++i) {
    int x = b[i];
    while (st.top() != x) {
      st1.push(st.top());
      ans += a[st.top() - 1];
      st.pop();
    }
    st.pop();
    while (!st1.empty()) {
      st.push(st1.top());
      st1.pop();
    }
    st.push(x);
  }
  cout << ans;
  return 0;
}
