#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())
template<class A, class B> auto& operator<<(ostream &o, pair<A, B> p) {
    return o << '(' << p.first << ", " << p.second << ')';
}
template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) {
    o << '{'; int i = 0; for(auto e : x) o << (", ")+2*!i++ << e; return o << '}';
}
#ifdef DEBUG
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "), ...); }(x), cerr << '\n'
#else
#define debug(...) {}
#endif

const int ALPH = 26;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, k;
    char ch;
    string s;
    cin >> n >> s >> k;
    vector<LL> val(ALPH);
    REP(i, k) {
        cin >> ch;
        cin >> val[ch - 'A'];
    }
    int prime = 1;
    FOR(i, 2, n) {
        if (n % i == 0) {
            prime = i;
            break;
        }
    }
    int cnt = 1, pwr = 1;
    while (pwr != n) {
        pwr *= prime;
        cnt++;
    }
    int jump = n, sign;
    vector<vector<LL> > dp(n);
    vector<LL> final(n);
    REP(i, n)
        dp[i].resize(ALPH);
    for (int i = cnt - 1; i >= 0; i--) {
        REP(j, n) {
            sign = s[j] - 'A';
            if (s[j] == '?') {
                REP(l, ALPH)
                    dp[j][l] = val[l];
                if (j >= jump) {
                    REP(l, ALPH) {
                        dp[j][l] += dp[j - jump][l];
                        if (dp[j - jump][l] == 0)
                            dp[j][l] = 0;
                    }
                }
            }
            else {
                dp[j][sign] = val[sign];
                if (j >= jump) {
                    dp[j][sign] += dp[j - jump][sign];
                    if (dp[j - jump][sign] == 0)
                        dp[j][sign] = 0;
                }
            }
        }
        LL mx, psum;
        REP(j, jump) {
            mx = 0;
            REP(l, ALPH)
                mx = max(mx, dp[n - jump + j][l]);
            if (jump == n)
                final[j] = mx;
            else {
                psum = 0;
                REP(l, prime)
                    psum += final[l * jump + j];
                final[j] = max(mx * (LL) (cnt - i), psum);
            }
        }

        jump /= prime;
        REP(j, n)
            fill(dp[j].begin(), dp[j].end(), 0);
    }
    cout << final[0] << '\n';
    return 0;
}