#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;

typedef long long ll;

int main() {
    int N;
    string S;
    cin >> N >> S;
    ll a, asum = 0, mins = 0, maxs = 0;
    rep(i, N) {
        cin >> a;
        if (S[i] == 'B') a = -a;
        asum += a;
        mins = min(mins, asum);
        maxs = max(maxs, asum);
    }
    cout << maxs - mins << "\n";
}