#include<iostream>
#include<iomanip>
#include<bitset>
#include<algorithm>
#include<string>
#include<vector>
#include<cstdio>
#include<cmath>
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;
    }
    vector<ll> sum(n);
    ll sa=0;
    for(int i=0;i<n;i++){
        sa+=a[i];
        sum[i]=sa;
    }
    sort(sum.begin(),sum.end());
    if(sum[0]>0 && sum[n-1]>0){
        cout << sum[n-1] << endl;
    }
    else if(sum[0]<0 && sum[n-1]<0){
        cout << abs(sum[0]) << endl;
    }
    else{
        cout << abs(sum[n-1]-sum[0]) << endl;
    }
    return 0;
}