#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
struct edge{
    int to, cap, rev; ll cost;
    edge(int to, int cap, ll cost, int rev):to(to), cap(cap), cost(cost), rev(rev){}
};
int V;
vector<edge> g[6060];
ll h[6060];
ll dist[6060];
int prevv[6060], preve[6060];
void add_edge(int from, int to, int cap, ll cost){
    edge e=edge(to, cap, cost, g[to].size());
    g[from].push_back(e);
    e=edge(from, 0, -cost, g[from].size()-1);
    g[to].push_back(e);
}
ll min_cost_flow(int s, int t, int f){
    using P=pair<ll, int>;
    const ll INF=1e18;
    ll res=0;
    fill(h, h+V, 0);
    while(f>0){
        priority_queue<P, vector<P>, greater<P>> que;
        fill(dist, dist+V, INF);
        dist[s]=0;
        que.push({0, 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<g[v].size(); i++){
                edge &e=g[v][i];
                if(e.cap>0 && dist[e.to]>dist[v]+e.cost+h[v]-h[e.to]){
                    dist[e.to]=dist[v]+e.cost+h[v]-h[e.to];
                    prevv[e.to]=v;
                    preve[e.to]=i;
                    que.push({dist[e.to], e.to});
                }
            }
        }
        for(int v=0; v<V; v++) h[v]+=dist[v];
        if(dist[t]==INF) return -1;
        int 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];
        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;
}
int n;
string str;
ll v[3030];
int main()
{
    cin>>n;
    cin>>str;
    for(int i=0; i<n; i++) cin>>v[i];
	vector<int> w[5];
	for(int i=0; i<n; i++){
		if(str[i]=='y') w[0].push_back(i);
		else if(str[i]=='u') w[1].push_back(i);
		else if(str[i]=='k') w[2].push_back(i);
		else w[3].push_back(i);
	}
	if(w[0].empty()){
		cout<<0<<endl;
		return 0;
	}
	int s=w[0][0], t=n;
	int S=n+1, T=n+2;
	w[4].push_back(t);
	V=n+3;
	add_edge(S, s, n/4, 0);
	add_edge(t, T, n/4, 0);
	ll ans=0;
	int f=0;
	for(int k=0; k<4; k++){
		for(int i=0; i<(int)w[k].size()-1; i++){
			add_edge(w[k][i], w[k][i+1], n/4, 0);
		}
		for(int i:w[k]){
			int j=lower_bound(w[k+1].begin(), w[k+1].end(), i)-w[k+1].begin();
			if(j<w[k+1].size()){
				add_edge(S, w[k+1][j], 1, 0);
				add_edge(w[k+1][j], i, 1, v[i]);
				add_edge(i, T, 1, 0);
				ans+=v[i];
				f++;
			}
		}
	}
	add_edge(s, t, n/4, 0);
	ans-=min_cost_flow(S, T, n/4+f);
    cout<<ans<<endl;
	return 0;
}