#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using mint = modint998244353;

int main() {
  int N; string S; cin >> N >> S;
  vector<ll> a(N);
  for (int i = 0; i < N; i++) {
    cin >> a[i];
    if (S[i] == 'B') a[i] *= -1;
  }
  vector<ll> sum(N + 1, 0);
  for (int i = 0; i < N; i++) sum[i + 1] += sum[i] + a[i];

  ll mins = 0, maxs = 0, ans = 0;
  for (int i = 0; i <= N; i++) {
    ans = max({ans, abs(mins - sum[i]), abs(maxs - sum[i])});
    mins = min(mins, sum[i]);
    maxs = max(maxs, sum[i]);
  }
  cout << ans << endl;
  return 0;
}