/**
*    author:  shu8Cream
*    created: 19.03.2021 23:17:00
**/

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i=0; i<(n); i++)
#define all(x) (x).begin(), (x).end()
using ll = long long;
using P = pair<int,int>;
using vi = vector<int>;
using vvi = vector<vi>;

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n; string s;
    cin >> n >> s;
    vector<ll> a(n),ra(n+1);
    rep(i,n) cin >> a[i];
    ll ans = 0;
    rep(i,n) if(s[i]=='B') a[i] = -a[i];
    rep(i,n) ra[i+1]=ra[i]+a[i];
    ll m=1e18, M=-1e18;
    rep(i,n+1){
        m=min(m,ra[i]);
        M=max(M,ra[i]);
    } 
    cout << abs(M-m) << endl;
}