#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/priority_queue.hpp>

#pragma GCC optimize("O3")
#pragma GCC target("sse4")
#pragma GCC target("avx2")

#define deb(x) cout << #x << " = " << x << "\n"
#define all(x) (x).begin(), (x).end()
#define len(x) (ll) x.size()
#define lsb(x) (x) & -(x)
#define l(x) (x << 1) + 1
#define r(x) (x << 1) + 2
#define v(x) (ll)(x - 'a')

#define xx first
#define yy second
#define mp make_pair
#define pb push_back
#define lb lower_bound
#define ub upper_bound

using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef pair <ll, ll> pii;
typedef pair <ld, ld> pld;
typedef pair <ll, ll> pll;

template <class T1, class T2 = less <T1>> using pb_heap = __gnu_pbds::priority_queue <T1, T2, binary_heap_tag>;
template <class T1, class T2 = null_type, class T3 = less <T1>> using pb_map = tree <T1, T2, T3, rb_tree_tag, tree_order_statistics_node_update>;
template <class T1, class T2 = null_type, class T3 = hash <T1>> using pb_umap = gp_hash_table <T1, T2, T3>;
template <class T1, class T2, class T3 = hash <T1>> using umap = unordered_map <T1, T2, T3>;
template <class T> using uset = unordered_set <T>;
template <class T> using vec = vector <T>;

const ll infll = numeric_limits <ll>::max() >> 1;
const ll inf = numeric_limits <ll>::max() >> 1;
const ll N = 1e5 + 1;
const ll L = 20;
ll n, p, k, mxval, dp[L][N], value[256];

string t;

void input() {
    cin >> n;
    cin >> t;
    cin >> k;
    for (ll i = 2; i <= n; ++i) {
        if (n % i == 0) {
            p = i;
            break;
        }
    }
    for (ll i = 0; i < k; ++i) {
        char chr;
        ll val;
        cin >> chr >> val;
        mxval = max(mxval, val);
        value[chr] = val;
    }
    value['?'] = mxval;
}

void solve() {
    if (n == 1) {
        cout << value[t[0]] << "\n";
        return;
    }
    ll c = 0;
    for (ll i = 1; i < n; i *= p) {
        c++;
    }
    for (ll i = c, d = n; i >= 0; --i, d /= p) {
        for (ll pos = 0; pos < d; ++pos) {
            bool allsame = true;
            char prevchar = t[pos];
            for (ll cur = pos; cur < n; cur += d) {
                if (t[cur] == '?') {
                    continue;
                }
                if (prevchar == '?') {
                    prevchar = t[cur];
                }
                allsame &= t[cur] == prevchar;
            }
            if (i != c) {
                for (ll nxt = pos, j = 0; j < p; ++j, nxt += d) {
                    dp[i][pos] += dp[i + 1][nxt];
                }
            }
            if (allsame) {
                dp[i][pos] = max(dp[i][pos], value[prevchar] * n / d * (c - i + 1));
            }
        }
    }
    cout << dp[0][0] << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    input();
    solve();
}