#include <bits/stdc++.h>
using namespace std;
int readint() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
long long n;
long long a[100005], d[100005][10];
char s[100005];
int main() {
  n = readint();
  scanf("%s", s + 1);
  for (int i = 1; i <= n; i++) a[i] = readint();
  memset(d, 0x3f, sizeof(d));
  d[0][0] = 0;
  for (int i = 1; i <= n; i++) {
    if (s[i] == 'h') {
      for (int j = 0; j <= 4; j++)
        if (j != 0 && j != 1) d[i][j] = d[i - 1][j];
      d[i][1] = min(d[i][1], min(d[i - 1][1], d[i - 1][0]));
      d[i][0] = min(d[i][0], d[i - 1][0] + a[i]);
    } else if (s[i] == 'a') {
      for (int j = 0; j <= 4; j++)
        if (j != 1 && j != 2) d[i][j] = d[i - 1][j];
      d[i][2] = min(d[i][2], min(d[i - 1][2], d[i - 1][1]));
      d[i][1] = min(d[i][1], d[i - 1][1] + a[i]);
    } else if (s[i] == 'r') {
      for (int j = 0; j <= 4; j++)
        if (j != 2 && j != 3) d[i][j] = d[i - 1][j];
      d[i][3] = min(d[i][3], min(d[i - 1][3], d[i - 1][2]));
      d[i][2] = min(d[i][2], d[i - 1][2] + a[i]);
    } else if (s[i] == 'd') {
      for (int j = 0; j <= 4; j++)
        if (j != 3 && j != 4) d[i][j] = d[i - 1][j];
      d[i][4] = min(d[i][4], min(d[i - 1][4], d[i - 1][3]));
      d[i][3] = min(d[i][3], d[i - 1][3] + a[i]);
    } else {
      for (int j = 0; j <= 4; j++) d[i][j] = d[i - 1][j];
    }
  }
  long long ans = 1ll << 60;
  for (int i = 0; i < 4; i++) ans = min(ans, d[n][i]);
  cout << ans << endl;
  return 0;
}
