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

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

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, INT_MAX - 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, INT_MAX - 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, INT_MAX - 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, INT_MAX - v[i]);
            Y = i;
        }
    }
    if (Y != -1) g.add_edge(a, Y, INT_MAX, 0);

    auto [flow, cost] = g.flow(a, b);
    long long ans = -(cost - (long long)4 * INT_MAX * flow);
    cout << ans << '\n';
}