#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;

    string s;
    cin >> s;

    vector<int> a(n);
    vector<ll> x(n + 1, 0);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        if (s[i] == 'B') a[i] *= -1;
        x[i + 1] = x[i] + a[i];
    }
    sort(x.begin(), x.end());

    cout << x.back() - x.front() << endl;

    return 0;
}