#include <bits/stdc++.h>
#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";

bool used[2005];
l_l dp[2005][5];
void f(ll s) {
    for(int i = s; i <= N; i++) {
        for(int j = 0; j < 5; j++) {
            dp[i][j] = {-INF, 0};
        }
    }
    dp[s][0] = {0, -1};
    for(int i = s; i < N; i++) {
        for(int j = 0; j < 5; j++) {
            chmax(dp[i+1][j], dp[i][j]);
            if(j < 4 and !used[i] and S[i] == yuki[j]) {
                l_l now = {dp[i][j].first + V[i], i};
                chmax(dp[i+1][j+1], now);
            }
        }
    }
    /*
    for(int j = 0; j < 5; j++) {
        for(int i = s; i <= N; i++) {
            cerr << "{" << dp[i][j].first << ", " << dp[i][j].second << "} ";
        }
        cerr << endl;
    }
    */
    ll nowi = N;
    ll nowj = 4;
    ll nowans = 0;
    while(nowj != 0) {
        ll newi = dp[nowi][nowj].second;
        nowans += V[newi];
        used[newi] = true;
        nowi = newi;
        nowj--;
    }
    ans += nowans;
}

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];
    for(int i = 0; i < N; i++) {
        if(S[i] != 'y') continue;
        vector<int> v;
        for(int j = i; j < N; j++) {
            if(v.size() == yuki.size()) continue;
            if(used[j]) continue;
            if(S[j] == yuki[v.size()]) v.push_back(j);
        }
        if(v.size() != yuki.size()) continue;
        s.push_back(i);
        for(auto j : v) used[j] = true;
    }
    /*
    for(auto tmp : s) cerr << tmp << " ";
    cerr << endl;
    */
    for(int i = 0; i < N; i++) used[i] = false;
    reverse(s.begin(), s.end());
    for(auto tmp : s) {
        f(tmp);
    }
    cout << ans << endl;
    return 0;
}