#include<iostream>
#include<iomanip>
#include<bitset>
#include<algorithm>
#include<string>
#include<vector>
#include<cstdio>
#include<cmath>
#include<queue>
#include<map>
#include<set>
using namespace std;
using ll=long long;

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;
    }
    ll sum = 0, Ama = 0, Ami = 10E16;
    for(int i = 0; i < N; i++){
        sum += A[i];
        Ama = max(Ama, sum);
        Ami = min(Ami, sum);
    }
    if((Ama / abs(Ama)) * (Ami / abs(Ami)) >= 0)cout << max(abs(Ama), abs(Ami)) << endl;
    else cout << abs(Ama - Ami) << endl;
    return 0;
}