#ifdef ONLINE_JUDGE
#pragma GCC target("avx2,avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using i128 = __int128_t;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define all(x) (x).begin(), (x).end()
constexpr char ln = '\n';
istream& operator>>(istream& is, __int128_t& x) {
    x = 0;
    string s;
    is >> s;
    int n = int(s.size()), it = 0;
    if (s[0] == '-') it++;
    for (; it < n; it++) x = (x * 10 + s[it] - '0');
    if (s[0] == '-') x = -x;
    return is;
}
ostream& operator<<(ostream& os, __int128_t x) {
    if (x == 0) return os << 0;
    if (x < 0) os << '-', x = -x;
    deque<int> deq;
    while (x) deq.emplace_front(x % 10), x /= 10;
    for (int e : deq) os << e;
    return os;
}
template<class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
    return os << "(" << p.first << ", " << p.second << ")";
}
template<class T> 
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "{";
    for (int i = 0; i < int(v.size()); i++) {
        if (i) os << ", ";
        os << v[i];
    }
    return os << "}";
}
template<class Container> inline int SZ(Container& v) { return int(v.size()); }
template<class T> inline void UNIQUE(vector<T>& v) { v.erase(unique(v.begin(), v.end()), v.end()); }
template<class T1, class T2> inline bool chmax(T1& a, T2 b) { if (a < b) {a = b; return true ;} return false ;}
template<class T1, class T2> inline bool chmin(T1& a, T2 b) { if (a > b) {a = b; return true ;} return false ;}
inline int topbit(int x) { return x == 0 ? -1 : 31 - __builtin_clz(x); }
inline int topbit(long long x) { return x == 0 ? -1 : 63 - __builtin_clzll(x); }
inline int botbit(int x) { return x == 0 ? 32 : __builtin_ctz(x); }
inline int botbit(long long x) { return x == 0 ? 64 : __builtin_ctzll(x); }
inline int popcount(int x) { return __builtin_popcount(x); }
inline int popcount(long long x) { return __builtin_popcountll(x); }
inline int kthbit(long long x, int k) { return (x>>k) & 1; }
inline constexpr long long TEN(int x) { return x == 0 ? 1 : TEN(x-1) * 10; }
inline void print() { cout << "\n"; }
template<class T>
inline void print(const vector<T>& v) {
    for (int i = 0; i < int(v.size()); i++) {
        if (i) cout << " ";
        cout << v[i];
    }
    print();
}
template<class T, class... Args>
inline void print(const T& x, const Args& ... args) {
    cout << x << " ";
    print(args...);
}
#ifdef MINATO_LOCAL
inline void debug_out() { cerr << endl; }
template <class T, class... Args>
inline void debug_out(const T& x, const Args& ... args) {
    cerr << " " << x;
    debug_out(args...);
}
#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
struct fast_ios { fast_ios() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

template<typename TF,typename TC>
struct PrimalDual{
    struct edge{
        int to;
        TF cap;
        TC cost;
        int rev;
        edge(){}
        edge(int to,TF cap,TC cost,int rev):
        to(to),cap(cap),cost(cost),rev(rev){}
    };

    static const TC INF;
    vector<vector<edge>> G;
    vector<TC> h,dist;
    vector<int> prevv,preve;

    PrimalDual(){}
    PrimalDual(int N):G(N),h(N),dist(N),prevv(N),preve(N){}

    void add_edge(int u,int v,TF cap,TC cost) {
        G[u].emplace_back(v,cap,cost,G[v].size());
        G[v].emplace_back(u,0,-cost,G[u].size()-1);
    }

    void dijkstra(int s) {
        struct P {
            TC first;
            int second;
            P(TC first,int second):first(first),second(second){}
            bool operator<(const P&a) const{return a.first<first;}
        };
        priority_queue<P> que;
        fill(dist.begin(),dist.end(),INF);

        dist[s] = 0;
        que.emplace(dist[s],s);
        while(!que.empty()) {
            P p=que.top(); que.pop();
            int v = p.second;
            if(dist[v] < p.first) continue;
            for(int i = 0; i < (int)G[v].size(); i++) {
                edge &e = G[v][i];
                if(e.cap == 0) continue;
                if(dist[v]+e.cost+h[v]-h[e.to]<dist[e.to]){
                dist[e.to]=dist[v]+e.cost+h[v]-h[e.to];
                prevv[e.to]=v;
                preve[e.to]=i;
                que.emplace(dist[e.to],e.to);
                }
            }
        }
    }

    TC flow(int s,int t,TF f,int &ok){
        TC res=0;
        fill(h.begin(),h.end(),0);
        while(f>0){
            dijkstra(s);
            if(dist[t] == INF) {
                ok = 0;
                return res;
            }

            for(int v = 0; v < (int)h.size(); v++)
                if(dist[v]<INF) h[v]=h[v]+dist[v];

            TF d=f;
            for(int v = t; v != s; v = prevv[v])
                d=min(d,G[prevv[v]][preve[v]].cap);

            f-=d;
            res = res + h[t]*d;
            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;
            }
        }
        ok = 1;
        return res;
    }
};
template<typename TF, typename TC>
const TC PrimalDual<TF, TC>::INF = numeric_limits<TC>::max()/2;

int main() {
    int N; cin >> N;
    string S; cin >> S;
    vector<int> A(N);
    rep(i,N) {
        if (S[i]=='u') A[i] = 1;
        else if (S[i]=='k') A[i] = 2;
        else if (S[i]=='i') A[i] = 3;
    }
    vector<ll> V(N);
    rep(i,N) cin >> V[i];

    PrimalDual<int,ll> g(N*2+2);
    int s = N*2;
    int t = N*2+1;
    rep(i,N) {
        g.add_edge(i,i+N,1,-V[i]);
        for (int j = i+1; j < N; j++) {
            if (A[j]==A[i]+1) g.add_edge(i+N,j,1,0);
        }
        if (A[i]==0) g.add_edge(s,i,1,0);
        if (A[i]==3) g.add_edge(i+N,t,1,0);
    }

    int ok = 0;
    cout << -g.flow(s,t,N/4,ok) << ln;
}