#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using pii = pair<int, int>;
template <class T>
using V = vector<T>;
template <class T>
using VV = V<V<T>>;

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define rep(i, n) rep2(i, 0, n)
#define rep2(i, m, n) for (int i = m; i < (n); i++)
#define per(i, b) per2(i, 0, b)
#define per2(i, a, b) for (int i = int(b) - 1; i >= int(a); i--)
#define ALL(c) (c).begin(), (c).end()
#define SZ(x) ((int)(x).size())

constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); }

template <class T, class U>
void chmin(T &t, const U &u) {
    if (t > u) t = u;
}
template <class T, class U>
void chmax(T &t, const U &u) {
    if (t < u) t = u;
}

template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << "(" << p.first << "," << p.second << ")";
    return os;
}

template <class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "{";
    rep(i, v.size()) {
        if (i) os << ",";
        os << v[i];
    }
    os << "}";
    return os;
}

#ifdef LOCAL
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << H;
    debug_out(T...);
}
#define debug(...) \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif

template <class C, class D>  // capacity, distance
struct MinCostFlow {
    struct edge {
        int to, rev;
        C cap;
        D cost;
        edge(int to, C cap, D cost, int rev)
            : to(to), cap(cap), cost(cost), rev(rev){};
    };

    using E = edge;

    const D INF = numeric_limits<D>::max() / D(3);

    int n;
    VV<E> g;
    V<D> h, dst;
    V<int> prevv, preve;

    MinCostFlow(int n) : n(n), g(n), h(n), dst(n), prevv(n), preve(n) {}

    void add_edge(int f, int t, C cap, D cost) {
        g[f].emplace_back(t, cap, cost, (int)g[t].size());
        g[t].emplace_back(f, 0, -cost, (int)g[f].size() - 1);
    }

    // true : no negative cycle
    bool init_negative(int s) {
        fill(h.begin(), h.end(), INF);
        h[s] = 0;
        for (int t = 0; t <= n; ++t) {
            for (int i = 0; i < n; ++i) {
                for (auto e : g[i]) {
                    if (!e.cap) continue;
                    if (h[e.to] > h[i] + e.cost && t == n) {
                        return false;
                    }
                    h[e.to] = min(h[e.to], h[i] + e.cost);
                }
            }
        }
        debug(h);
        return true;
    }

    D exec(int s, int t, C f) {
        D res = 0;
        using Data = pair<D, int>;
        while (f > 0) {
            priority_queue<Data, vector<Data>, greater<Data>> que;
            fill(dst.begin(), dst.end(), INF);
            dst[s] = 0;
            que.push(Data(0, s));

            while (!que.empty()) {
                auto p = que.top();
                que.pop();
                int v = p.second;
                if (dst[v] < p.first) continue;

                rep(i, g[v].size()) {
                    auto e = g[v][i];
                    D nd = dst[v] + e.cost + h[v] - h[e.to];
                    if (e.cap > 0 && dst[e.to] > nd) {
                        dst[e.to] = nd;
                        prevv[e.to] = v;
                        preve[e.to] = i;
                        que.push(Data(dst[e.to], e.to));
                    }
                }
            }

            if (dst[t] >= INF) return res;

            rep(i, n) {
                if (h[i] <= INF - dst[i]) {
                    h[i] += dst[i];
                } else {
                    h[i] = INF;
                }
            }
            if (h[t] >= INF) return res;

            C d = f;
            for (int v = t; v != s; v = prevv[v]) {
                d = min(d, g[prevv[v]][preve[v]].cap);
            }
            f -= d;
            res += d * h[t];
            if (h[t] >= 0) break;
            for (int v = t; v != s; v = prevv[v]) {
                edge &e = g[prevv[v]][preve[v]];
                e.cap -= d;
                g[v][e.rev].cap += d;
            }
        }

        return res;
    }
};

const string T = "yuki";

int main() {
    int N;
    string S;
    cin >> N >> S;
    V<ll> a(N);
    rep(i, N) cin >> a[i];
    int cnt = N * 5;
    MinCostFlow<ll, ll> g(cnt);

    rep(i, N - 1) {
        rep(j, 5) { g.add_edge(j * N + i, j * N + i + 1, N, 0); }
    }
    rep(i, N) {
        rep(j, 4) {
            if (S[i] == T[j]) {
                g.add_edge(j * N + i, (j + 1) * N + i, 1, -a[i]);
            }
        }
    }
    g.init_negative(0);
    cout << -g.exec(0, 5 * N - 1, N) << endl;

    return 0;
}