#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 7;
long long arr[maxn];
string s;
int main() {
  std::ios::sync_with_stdio(false);
  int n;
  cin >> n;
  long long tot = 0;
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
    arr[i] *= 2;
    tot += arr[i];
  }
  cin >> s;
  long long W = 0, G = 0, flag = 5;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'G')
      G += arr[i];
    else if (s[i] == 'W')
      W += arr[i], flag = 3;
    long long cur = arr[i], sta;
    sta = min(cur / 2, W), tot += sta * 2, cur -= sta * 2, W -= sta;
    sta = min(cur / 2, G), tot += sta * 4, cur -= sta * 2, G -= sta;
    tot += flag * cur;
  }
  cout << tot / 2 << endl;
}
