/*{{{*/
#include <bits/stdc++.h>
#ifdef LOCAL
int c_ = 0;
#define cout (c_?cerr:cout)
#define debug(...) \
{if(!c_++)cerr<<"\033[96;1m"; \
__VA_ARGS__; \
if(!--c_)cerr<<"\033[0m";}
#else
#define debug(...) {}
#endif
#define assrt(...) debug(\
if (not (__VA_ARGS__)) \
    exit((cerr << __LINE__ << ": " << #__VA_ARGS__ << '\n', 0));\
)
#define st first
#define nd second
#define all(...) (__VA_ARGS__).begin(), (__VA_ARGS__).end()
using namespace std; using ll = long long; using ld = long double;
template < typename t > using V = vector< t >;
template < typename t, size_t s > using A = array< t, s >;
void print() {cout << '\n';}
template< typename t, typename... v >
void print(const t& a, const v&... b)
{cout << a << (sizeof...(b)?" ":""); print(b...);}
template< typename t > void print_range(t a, const t& b)
{ while (a != b) cout << (*a++) << ' '; cout << '\n';}
#define dump(...) debug(print(#__VA_ARGS__,'=',__VA_ARGS__))
#define dump_range(...) debug(cerr<<#__VA_ARGS__ << ": "; print_range(__VA_ARGS__))
/*}}}*/

constexpr int nax = 1e5;

int n, k, p = 2, m, val[26], mks; string s;

ll dp(const int r, const int d, const int u) {
    int a = -1;
    int i = u;
    do {
        if (s[i] != '?') {
            if ((int)(s[i] - 'A') != a) {
                if (a == -1) {
                    a = (int)(s[i] - 'A');
                } else {
                    a = 26;
                }
            }
        } 
        i += d;
        if (i >= n) i -= n;
    } while (i != u);

    dump(r, d, u, a);

    ll res = 0;

    if (a != 26) {
        if (a != -1) {
            res = max(res, (ll)(m - r + 1) * (ll)val[a] * (n / d));
        } else {
            res = max(res, (ll)(m - r + 1) * (ll)mks * (n / d));
        }
    }

    if (p != 1 and d * p <= n) {
        ll tmp = 0;
        for (int i = 0; i < p; ++i) {
            tmp += dp(r + 1, d * p, i * d);
        }
        res = max(res, tmp);
    }

    return res;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n;
    cin >> s;
    cin >> k;

    for (int i = 0; i < k; ++i) {
        char c; int v; cin >> c >> v;
        val[c - 'A'] = v;
        mks = max(v, mks);
    }

    if (n == 1) {
        p = 1;
    }

    while ((n % p) != 0) {
        ++p;
    }

    int tmp = n;
    while (p != 1 and ((tmp % p) == 0)) {
        tmp /= p;
        ++m;
    }

    if (n == 1) {
        m = 0;
    }

    dump(p);
    dump(m);
    dump(n);

    cout << dp(0, 1, 0) << '\n';
}