#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  string S;
  cin >> S;
  vector<int> a(N);
  for (int i = 0; i < N; i++){
    cin >> a[i];
  }
  for (int i = 0; i < N; i++){
    if (S[i] == 'B'){
      a[i] *= -1;
    }
  }
  vector<long long> s(N + 1, 0);
  for (int i = 0; i < N; i++){
    s[i + 1] = s[i] + a[i];
  }
  long long mn = 0, mx = 0;
  for (int i = 1; i <= N; i++){
    mn = min(mn, s[i]);
    mx = max(mx, s[i]);
  }
  cout << mx - mn << endl;
}