#include <bits/stdc++.h>
using namespace std;
int INF = (int)1e9;
long long INFINF = (long long)1e18 + 10;
const long double PI = 3.14159265358979323846;
long long GCD(long long, long long);
long long LCM(long long, long long);
long long power(int, int);
long long choose(long long, long long);
int ones(long long);
void extendedEuclid(long long, long long);
long long MMI(long long, long long);
void fastscan(int &);
vector<int> id(200005);
void initial(int n) {
  for (int i = 0; i <= n; i++) {
    id[i] = i;
  }
}
int root(int x) {
  while (id[x] != x) {
    id[x] = id[id[x]];
    x = id[x];
  }
  return x;
}
void union1(int a, int b) {
  int p = root(a);
  int q = root(b);
  id[p] = id[q];
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n;
  cin >> n;
  vector<long long> a(4);
  string s;
  cin >> s;
  for (int i = 0; i < n; i++) {
    long long x;
    cin >> x;
    if (s[i] == 'h') {
      a[0] += x;
    } else if (s[i] == 'a') {
      a[1] = min(a[1] + x, a[0]);
    } else if (s[i] == 'r') {
      a[2] = min(a[2] + x, a[1]);
    } else if (s[i] == 'd') {
      a[3] = min(a[3] + x, a[2]);
    }
  }
  cout << a[3] << endl;
  return 0;
}
long long GCD(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return GCD(b, a % b);
}
long long LCM(long long a, long long b) {
  return (max(a, b) / GCD(a, b)) * min(a, b);
}
long long power(int a, int n) {
  unsigned long long int result = 1, x = a;
  while (n > 0) {
    if (n % 2 == 1) result = result * x;
    x = x * x;
    n = n / 2;
  }
  return result;
}
long long choose(long long n, long long k) {
  if (k == 0) return 1;
  return (n * choose(n - 1, k - 1)) / k;
}
int ones(long long n) {
  int c = 0;
  while (n) {
    n = n & (n - 1);
    c++;
  }
  return c;
}
long long d, x, y;
void extendedEuclid(long long A, long long B) {
  if (B == 0) {
    d = A;
    x = 1;
    y = 0;
  } else {
    extendedEuclid(B, A % B);
    int temp = x;
    x = y;
    y = temp - (A / B) * y;
  }
}
long long MMI(long long a, long long p) {
  extendedEuclid(a, p);
  if (d == 1 && p != 1)
    return ((x % p) + p) % p;
  else
    return -1;
}
void fastscan(int &number) {
  bool negative = false;
  register int c;
  number = 0;
  c = getchar();
  if (c == '-') {
    negative = true;
    c = getchar();
  }
  for (; (c > 47 && c < 58); c = getchar()) number = number * 10 + c - 48;
  if (negative) number *= -1;
}
