#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define REP(i, n) FOR(i, 0, n)
#define ll long long

using namespace std;

const int MAXN = 100100;

ll val[30];
char arr[MAXN];
int n;
int pot[MAXN];
ll maxi;
ll prost;

ll solve(int x, int step) {

    char tr = '?';
    int t = x, flag = 1;
    REP(i, n / step) {
        if (arr[t] != '?') {
            if (tr == '?')         tr = arr[t];
            else if (tr != arr[t]) flag = 0;
        }

        if (!flag) break;
        t = (t + step) % n;
    }

    ll out = 0;
    if (flag) {
        ll steps_left = pot[n / step] + 1;

        if (tr == '?') out = steps_left * (n / step) * maxi;
        else           out = steps_left * (n / step) * val[tr - 'A'];
    }

    ll out2 = 0;
    if (step < n) {
        REP(i, prost) {
            out2 += solve((x + i * step) % n, step * prost);
        }
    }

    return max(out, out2);
}

int main() {
    ios_base::sync_with_stdio(false);

    cin >> n;

    FOR(i, 2, n + 1) {
        if (n % i == 0) {
            prost = i;
            break;
        }
    }
    assert(prost > 1);

    ll tr = 1;
    int ind = 0;
    while (tr <= n) {
        pot[tr] = ind;
        tr *= prost;
        ind++;
    }

    string s;
    cin >> s;
    REP(i, n) arr[i] = s[i];

    int k;
    cin >> k;
    REP(i, k) {
        char c; int v;
        cin >> c >> v;
        val[c - 'A'] = v;

        if (v >= maxi) maxi = v;
    }

    cout << solve(0, 1) << "\n";

    return 0;
}