#include<bits/stdc++.h>
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)
#define mod 1000000007
using namespace std;
void Onigiri()
{
  int n;cin>>n;
  string s;cin>>s;
  int a[n];rep(i,n)cin>>a[i];
  int dp[n][4];
  dp[0][0]=0;dp[0][1]=0;
  dp[0][2]=0;dp[0][3]=0;
  for(int i=0;i<n;i++)
  {
    if(i!=0)dp[i][0]=dp[i-1][0],dp[i][1]=dp[i-1][1],dp[i][2]=dp[i-1][2],dp[i][3]=dp[i-1][3];
    if(s[i]=='h')
    {
      dp[i][0]+=a[i];
    }
    else if(s[i]=='a')
    {
      dp[i][1]=min(a[i]+dp[i][1],dp[i][0]);
    }
    else if(s[i]=='r')
    {
       dp[i][2]=min(a[i]+dp[i][2],dp[i][1]);
    }
    else if(s[i]=='d')
    {
      dp[i][3]=min(a[i]+dp[i][3],dp[i][2]);
    }
  }
  cout<<min(min(dp[n-1][3],dp[n-1][2]),min(dp[n-1][1],dp[n-1][0]));

}
signed main()
{
  ios_base::sync_with_stdio(false);cin.tie(NULL);
  #ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
  #endif  
  int t=1;
 // cin>>t;
  while(t--)
  {
    Onigiri();
    cout<<"\n";
  }
  return 0;

}