#pragma GCC optimize("Ofast")
#pragma GCC target ("sse4")

#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
#include<array>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;
typedef double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acosl(-1.0);

ll mod_pow(ll x, ll n, ll m = mod) {
    ll res = 1;
    while (n) {
        if (n & 1)res = res * x % m;
        x = x * x % m; n >>= 1;
    }
    return res;
}
struct modint {
    ll n;
    modint() :n(0) { ; }
    modint(ll m) :n(m) {
        if (n >= mod)n %= mod;
        else if (n < 0)n = (n % mod + mod) % mod;
    }
    operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, ll n) {
    if (n == 0)return modint(1);
    modint res = (a * a) ^ (n / 2);
    if (n % 2)res = res * a;
    return res;
}

ll inv(ll a, ll p) {
    return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

//const int max_n = 1 << 18;
//modint fact[max_n], factinv[max_n];
//void init_f() {
//    fact[0] = modint(1);
//    for (int i = 0; i < max_n - 1; i++) {
//        fact[i + 1] = fact[i] * modint(i + 1);
//    }
//    factinv[max_n - 1] = modint(1) / fact[max_n - 1];
//    for (int i = max_n - 2; i >= 0; i--) {
//        factinv[i] = factinv[i + 1] * modint(i + 1);
//    }
//}
//modint comb(int a, int b) {
//    if (a < 0 || b < 0 || a < b)return 0;
//    return fact[a] * factinv[b] * factinv[a - b];
//}


int max_n;
const int mn = 100000;
struct edge {
	int to, cap; ll cost; int rev;
};
vector<edge> G[mn];
P par[mn];
ll dist[mn];
void add_edge(int from, int to, int cap, ll cost) {
	G[from].push_back({ to,cap,cost,(int)G[to].size() });
	G[to].push_back({ from,0,-cost,(int)G[from].size() - 1 });
	max_n = max({ max_n, from + 1, to + 1 });
}
void add_edge2(int from, int to, int cap, ll cost) {
	G[from].push_back({ to,cap,cost,-1 });
	//G[to].push_back({ from,0,-cost,(int)G[from].size() - 1 });
	max_n = max({ max_n, from + 1, to + 1 });
}
LP minimum_road(int s, int t) {
	fill(par, par + max_n, P{ -1,-1 });
	fill(dist, dist + max_n, INF);
	dist[s] = 0;
	priority_queue<LP, vector<LP>, greater<LP>> q; q.push({ 0,s });
	while (!q.empty()) {
		LP p = q.top(); q.pop();
		int id = p.second;
		if (id == t)continue;
		if (p.first > dist[id])continue;
		rep(j, G[id].size()) {
			if (G[id][j].cap > 0) {
				int to = G[id][j].to;
				ll nd = p.first + G[id][j].cost;
				if (nd < dist[to]) {
					dist[to] = nd;
					par[to] = { id,j };
					q.push({ dist[to],to });
				}
			}
		}
	}
	int cur = t;
	int f = mod;
	while (cur != s) {
		int p = par[cur].first, j = par[cur].second;
		if (p < 0)return { -1,-1 };
		f = min(f, G[p][j].cap);
		cur = p;
	}
	cur = t;
	while (cur != s) {
		int p = par[cur].first, j = par[cur].second;
		if (p < 0)return { -1,-1 };
		G[p][j].cap -= f;
		if (G[p][j].rev >= 0) {
			G[cur][G[p][j].rev].cap += f;
		}
		cur = p;
	}
	return { dist[t],f };
}
ll minimum_cost_flow(int s, int t, int k) {
	ll ret = 0;
	rep(i, k) {
		LP z = minimum_road(s, t);
		if (z.first < 0)return -1;
		if (k - i <= z.second) {
			ret += z.first * (k - i); break;
		}
		i += z.second - 1;
		ret += z.first * z.second;
	}
	return ret;
}

void solve() {
	int n; cin >> n;
	string s; cin >> s;
	vector<ll> v(n); rep(i, n)cin >> v[i];
	string yuki = "yuki";
	int sta = 5 * n, goa = 5 * n + 1;
	vector<int> d(goa + 1);
	ll ans = 0;
	rep(i, n) {
		if (i + 1 < n) {
			rep(j, 5) {
				add_edge(i + j * n, i + 1 + j * n, mod, 0);
			}
		}
		int loc = yuki.find(s[i]);
		//cout << i << " " << loc << "\n";
		if (loc < 4) {
			//add_edge(i + loc * n, i + (loc + 1) * n, 1, -v[i]);
			ans -= v[i];
			int fr = i + loc * n;
			int to = i + (loc + 1) * n;
			add_edge(to,fr, 1, v[i]);
			d[to]++;
			d[fr]--;
		}
	}
	add_edge(sta, 0, mod, 0);
	add_edge(5 * n - 1, goa, mod, 0);
	add_edge(goa, sta, mod, 0);
	int S = goa + 1; int T = S + 1;
	int sum = 0;
	rep(i, S) {
		if (d[i] < 0) {
			add_edge(i, T, -d[i], 0);
		}
		else {
			sum += d[i];
			add_edge(S, i, d[i], 0);
		}
	}
	ans += minimum_cost_flow(S, T, sum);
	cout << -ans << "\n";
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
   // cout << fixed << setprecision(15);
    //init_f();
    //init();
    //expr();
    //int t; cin >> t; rep(i, t)
    solve();
    return 0;
}