#include <bits/stdc++.h>
#include <atcoder/mincostflow>
#define endl "\n"
using namespace std;
typedef long long ll;
typedef pair<ll, ll> l_l;
typedef pair<int, int> i_i;
template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}

const long long INF = 1e18;
//const ll mod = 1000000007;
ll N;
string S;
vector<ll> V;
ll ans = 0;
vector<ll> s;
string yuki = "yuki";

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> N >> S;
    V.resize(N);
    for(int i = 0; i < N; i++) cin >> V[i];
    ll s = 4 * N;
    ll t = s + 1;
    atcoder::mcf_graph<ll, ll> g(t + 1);
    g.add_edge(s, 0, N, 0);
    for(int i = 0; i + 1 < N; i++) {
        for(int j = 0; j < 4; j++) {
            g.add_edge(4 * i + j, 4 * (i + 1) + j, N, 0);
        }
    }
    for(int i = 0; i < N; i++) {
        for(int j = 0; j < 4; j++) {
            if(S[i] != yuki[j]) continue;
            if(j != 3) {
                g.add_edge(4*i+j, 4*i+j+1, 1, (ll)1e9 - V[i]);
            } else {
                g.add_edge(4*i+j, t, 1, (ll)1e9 - V[i]);
            }
        }
    }
    l_l tmp = g.flow(s, t);
    ll ans = tmp.first * (ll)1e9 * 4 - tmp.second;
    cout << ans << endl;
    return 0;
}