#include <bits/stdc++.h>

using namespace std;

#define BITS __builtin_popcountll
typedef long long ll;




const ll MAX = (ll)1e5 + 5;


ll segTree[MAX << 2], m;


void Build(ll node, ll nodeL, ll nodeR, const string& s) {

    if (nodeL == nodeR) {
        segTree[node] |= (1 << (ll)(s[nodeL] - 'a'));
        return;
    }

    ll mid = (nodeL + nodeR) >> 1;
    ll leftNode = node + 1;
    ll rightNode = node + ((mid - nodeL + 1) << 1);
    Build(leftNode, nodeL, mid, s);
    Build(rightNode, mid + 1, nodeR, s);
    segTree[node] = (segTree[leftNode] | segTree[rightNode]);

}


pair<ll, ll> Query(ll node, ll nodeL, ll nodeR, ll l, ll r,
                      ll mask, ll k) {

    if (l > r) {
        return {0, 0};
    }

    ll mid = (nodeL + nodeR) >> 1;
    ll leftNode = node + 1;
    ll rightNode = node + ((mid - nodeL + 1) << 1);

    if ((nodeL == l) && (nodeR == r)) {
        if (BITS(mask | segTree[node]) >= k) {
            if (nodeL == nodeR) {
                return {(mask | segTree[node]), nodeR + 1};
            }
            else {

                if (BITS(mask | segTree[leftNode]) >= k) {
                    return Query(leftNode, nodeL, mid, l, min(mid, r),
                                  mask, k);
                }
                else {
                    return Query(rightNode, mid + 1, nodeR, max(mid + 1, l), r,
                                 (mask | segTree[leftNode]), k);
                }

            }
        }
        else {
            return {(mask | segTree[node]), 0};
        }
    }

    pair<ll, ll> leftTry = Query(leftNode, nodeL, mid, l, min(mid, r),
                                    mask, k);

    if (BITS(leftTry.first) == k) {
        return leftTry;
    }

    return Query(rightNode, mid + 1, nodeR, max(mid + 1, l), r,
                 (mask | leftTry.first), k);

}


long long Solve(ll i, const vector<ll>& c, vector<long long>& dp) {

    if (i == (ll)dp.size()) {
        return 0;
    }

    long long& res = dp[i];
    if (res != -1) {
        return res;
    }

    res = LONG_LONG_MAX;
    for (ll j = 0; j < m; j++) {

        ll newIndex = Query(0, 0, (ll)dp.size() - 1, i, (ll)dp.size() - 1,
                              0, j + 1).second;

        res = min(res, Solve(newIndex, c, dp) + c[j]);
        if (newIndex == (ll)dp.size()) {
            break;
        }

    }

    return res;

}


int main() {

    ios_base :: sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    ll n;
    cin >> n;
    string s;
    cin >> s;

    cin >> m;
    vector<ll> c(26);
    for (ll i = 0; i < m; i++) {
        cin >> c[i];
    }

    Build(0, 0, n - 1, s);

    vector<long long> dp(n, -1);
    cout << Solve(0, c, dp);

    return 0;

}