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

__attribute__((constructor))
void fast_io() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
}

template <class Cap, class Cost>
struct mcf_graph {
public:
    mcf_graph() {}
    mcf_graph(int n) : _n(n), g(n), neg(false) {}

    int add_edge(int from, int to, Cap cap, Cost cost) {
        assert(0 <= from && from < _n);
        assert(0 <= to && to < _n);
        assert(0 <= cap);
        if (cost < 0) neg = true;
        int m = int(pos.size());
        pos.push_back({from, int(g[from].size())});
        int from_id = int(g[from].size());
        int to_id = int(g[to].size());
        if (from == to) to_id++;
        g[from].push_back(_edge{to, to_id, cap, cost});
        g[to].push_back(_edge{from, from_id, 0, -cost});
        return m;
    }

    struct edge {
        int from, to;
        Cap cap, flow;
        Cost cost;
    };

    edge get_edge(int i) {
        int m = int(pos.size());
        assert(0 <= i && i < m);
        auto _e = g[pos[i].first][pos[i].second];
        auto _re = g[_e.to][_e.rev];
        return edge{
            pos[i].first, _e.to, _e.cap + _re.cap, _re.cap, _e.cost,
        };
    }
    std::vector<edge> edges() {
        int m = int(pos.size());
        std::vector<edge> result(m);
        for (int i = 0; i < m; i++) {
            result[i] = get_edge(i);
        }
        return result;
    }

    std::pair<Cap, Cost> flow(int s, int t) {
        return flow(s, t, std::numeric_limits<Cap>::max());
    }
    std::pair<Cap, Cost> flow(int s, int t, Cap flow_limit) {
        return slope(s, t, flow_limit).back();
    }
    std::vector<std::pair<Cap, Cost>> slope(int s, int t) {
        return slope(s, t, std::numeric_limits<Cap>::max());
    }
    std::vector<std::pair<Cap, Cost>> slope(int s, int t, Cap flow_limit) {
        assert(0 <= s && s < _n);
        assert(0 <= t && t < _n);
        assert(s != t);
        std::vector<Cost> dual(_n, 0), dist(_n);
        std::vector<int> pv(_n), pe(_n);
        std::vector<bool> vis(_n);
        auto neg_dual_ref = [&]() {
            std::fill(dist.begin(), dist.end(),
                      std::numeric_limits<Cost>::max());
            std::fill(pv.begin(), pv.end(), -1);
            std::fill(pe.begin(), pe.end(), -1);
            dist[s] = 0;
            bool update = true;
            while (update) {
                update = false;
                for (int v = 0; v < _n; v++) {
                    if (dist[v] == numeric_limits<Cost>::max()) continue;
                    for (int i = 0; i < int(g[v].size()); ++i) {
                        auto e = g[v][i];
                        if (!e.cap) continue;
                        if (dist[e.to] > dist[v] + e.cost) {
                            dist[e.to] = dist[v] + e.cost;
                            pv[e.to] = v;
                            pe[e.to] = i;
                            update = true;
                        }
                    }
                }
            }
            if (dist[t] == numeric_limits<Cost>::max()) return false;
            for (int v = 0; v < _n; ++v) {
                if (dist[v] == numeric_limits<Cost>::max()) continue;
                dual[v] -= dist[t] - dist[v];
            }
            return true;
        };
        auto dual_ref = [&]() {
            std::fill(dist.begin(), dist.end(),
                      std::numeric_limits<Cost>::max());
            std::fill(pv.begin(), pv.end(), -1);
            std::fill(pe.begin(), pe.end(), -1);
            std::fill(vis.begin(), vis.end(), false);
            struct Q {
                Cost key;
                int to;
                bool operator<(Q r) const { return key > r.key; }
            };
            std::priority_queue<Q> que;
            dist[s] = 0;
            que.push(Q{0, s});
            while (!que.empty()) {
                int v = que.top().to;
                que.pop();
                if (vis[v]) continue;
                vis[v] = true;
                if (v == t) break;
                for (int i = 0; i < int(g[v].size()); i++) {
                    auto e = g[v][i];
                    if (vis[e.to] || !e.cap) continue;
                    Cost cost = e.cost - dual[e.to] + dual[v];
                    if (dist[e.to] - dist[v] > cost) {
                        dist[e.to] = dist[v] + cost;
                        pv[e.to] = v;
                        pe[e.to] = i;
                        que.push(Q{dist[e.to], e.to});
                    }
                }
            }
            if (!vis[t]) {
                return false;
            }

            for (int v = 0; v < _n; v++) {
                if (!vis[v]) continue;
                dual[v] -= dist[t] - dist[v];
            }
            return true;
        };
        Cap flow = 0;
        Cost cost = 0, prev_cost_per_flow = -1;
        std::vector<std::pair<Cap, Cost>> result;
        result.push_back({flow, cost});
        bool first = true;
        while (flow < flow_limit) {
            if (first && neg) {
                if (!neg_dual_ref()) break;
                first = false;
            } else {
                if (!dual_ref()) break;
            }
            Cap c = flow_limit - flow;
            for (int v = t; v != s; v = pv[v]) {
                c = std::min(c, g[pv[v]][pe[v]].cap);
            }
            for (int v = t; v != s; v = pv[v]) {
                auto& e = g[pv[v]][pe[v]];
                e.cap -= c;
                g[v][e.rev].cap += c;
            }
            Cost d = -dual[s];
            flow += c;
            cost += c * d;
            if (prev_cost_per_flow == d) {
                result.pop_back();
            }
            result.push_back({flow, cost});
            prev_cost_per_flow = d;
        }
        return result;
    }

private:
    int _n;

    struct _edge {
        int to, rev;
        Cap cap;
        Cost cost;
    };

    std::vector<std::pair<int, int>> pos;
    std::vector<std::vector<_edge>> g;

    bool neg;
};

int main() {
    int n;
    string s;
    cin >> n >> s;
    vector<int> v(n);
    for (auto& vi : v) cin >> vi;

    mcf_graph<int, long long> g(n + 2);
    int a = n, b = n + 1;
    int Y = -1, U = -1, K = -1, I = -1;
    for (int i = n-1; i >= 0; --i) {
        if (s[i] == 'i') {
            g.add_edge(i, b, 1, -v[i]);
            if (I != -1) g.add_edge(i, I, INT_MAX, 0);
            I = i;
        } else if (s[i] == 'k') {
            if (K != -1) g.add_edge(i, K, INT_MAX, 0);
            if (I != -1) g.add_edge(i, I, 1, -v[i]);
            K = i;
        } else if (s[i] == 'u') {
            if (U != -1) g.add_edge(i, U, INT_MAX, 0);
            if (K != -1) g.add_edge(i, K, 1, -v[i]);
            U = i;
        } else if (s[i] == 'y') {
            if (Y != -1) g.add_edge(i, Y, INT_MAX, 0);
            if (U != -1) g.add_edge(i, U, 1, -v[i]);
            Y = i;
        }
    }
    if (Y != -1) g.add_edge(a, Y, INT_MAX, 0);

    auto [_, ans] = g.flow(a, b);
    ans = -ans;
    cout << ans << '\n';
}