#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, sat = 0;
  cin >> n;
  int a[n], b[n], c[n - 1];
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    cin >> b[i];
  }
  for (int i = 1; i <= n - 1; i++) {
    cin >> c[i];
  }
  for (int i = 1; i <= n; i++) {
    sat = sat + b[a[i]];
  }
  for (int i = 1; i <= n - 1; i++) {
    if ((a[i] + 1) == a[i + 1]) sat = sat + c[a[i + 1]];
  }
  cout << sat;
  return 0;
}
