#include <bits/stdc++.h>
using namespace std;
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  long long f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n;
  string s;
  cin >> n >> s;
  long long a[n];
  for (long long i = 0; i < n; i++) cin >> a[i];
  long long dp[n][4];
  for (long long i = 0; i < n; i++) {
    dp[i][0] = dp[i][1] = dp[i][2] = dp[i][3] = 0;
  }
  for (long long i = 0; i < n; i++) {
    if (i != 0) {
      for (long long j = 0; j < 4; j++) {
        dp[i][j] = dp[i - 1][j];
      }
    }
    if (s[i] == 'h') {
      dp[i][0] += a[i];
    }
    if (s[i] == 'a') {
      dp[i][1] = min(a[i] + dp[i][1], dp[i][0]);
    }
    if (s[i] == 'r') {
      dp[i][2] = min(a[i] + dp[i][2], dp[i][1]);
    }
    if (s[i] == 'd') {
      dp[i][3] = min(a[i] + dp[i][3], dp[i][2]);
    }
  }
  long long ans = min({dp[n - 1][0], dp[n - 1][1], dp[n - 1][2], dp[n - 1][3]});
  cout << ans;
}
