#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
#include <bits/stdc++.h>
using namespace std;
#define sim template <class c
#define mor > muu & operator<<(
#define ris return *this
#define R22(r) sim> typename enable_if<1 r sizeof(dud<c>(0)),muu&>::type operator<<(c g) {
sim> struct rge {c b, e;};
sim> rge<c> range(c i, c j) {return {i, j};}
sim> auto dud(c*r)->decltype(cerr << *r);
sim> char dud(...);
struct muu {
	#ifdef LOCAL
	stringstream a;
	~muu() {cerr << a.str() << endl;}
	R22(<) a << boolalpha << g; ris;}
	R22(==) ris << range(begin(g), end(g));}
	sim, class b mor pair <b,c> r) {ris << "(" << r.first << ", " << r.second << ")";}
	sim mor rge<c> u) {
		a << "[";
		for (c i = u.b; i != u.e; ++i)
			*this << ", " + 2 * (i == u.b) << *i;
		ris << "]";
	}
	#define qel(t) sim, class d, class...e mor t<c,d,e...> r) {ris << *(d*)&r;}
	qel(stack) qel(queue) qel(priority_queue)
	template <class...c mor tuple<c...> r) {
		a << "(";
		int q = 0;
		apply([&](c...x){((*this << ", " + 2 * !q++ << x), ...);}, r);
		ris << ")";
	}
	#else
	sim mor const c&){ris;}
	#endif
};
#define imie(r...) "[" #r ": " << (r) << "] "
#define arr(a, i) "[" #a imie(i) ": " << a[i] << "] "
#define arr2(a, i, j) "[" #a imie(i) imie(j) ": " << a[i][j] << "] "
#define range(a, b) "[[" #a ", " #b "): " << range(a, b) << "] "
#define debug muu() << __FUNCTION__ << "#" << __LINE__ << ": "
using ll = long long; using ld = long double; using unt = unsigned int;
using pii = pair<int, int>; using vpii = vector <pii>; using ull = unsigned long long; using vi = vector<int>;
using Pii = pii; using vll = vector <ll>;
sim> void mini(c &a, const c& b) {if (a > b) a = b;} sim> void maxi(c &a, const c& b) {if (a < b) a = b;}
const int A = 26, nax = 1e5 + 44;
const ll llinf = 1e16;
ll which[A];
char word[nax];
int p = -1;
array <ll, A + 1> run(string x) {
	if (x.size() == 1u) {
		array<ll, A + 1> ans;
		fill(ans.begin(), ans.end(), 0);
		if (x[0] == '\?')
			for (int i = 0; i < A; ++i) ans[i] = which[i];
		else {
			for (int i = 0; i < A; ++i) ans[i] = -llinf;
			ans[x[0] - 'A'] = which[x[0] - 'A'];
		}
		debug imie(x) imie(ans);
		return ans;
	}
	else {
		assert(x.size() % p == 0);
		vector <string> out(p);
		for (int i = 0; i < (int) x.size(); ++i) out[i % p].push_back(x[i]);
		array<ll, A + 1> ans;
		fill(ans.begin(), ans.end(), 0);
		for (int i = 0; i < p; ++i) {
			auto r = run(out[i]);
			for (int j = 0; j < A; ++j)
				ans[j] += r[j];
			ans[A] += *max_element(r.begin(), r.end());
		}
		for (int i = 0; i < A; ++i)
			ans[i] += x.size() * which[i];
		for (auto &x : ans) maxi(x, -llinf);
		debug imie(x) imie(ans);
		return ans;
	}
}
int main() {
	int n, k;
	scanf("%d%s%d", &n, word, &k);
	for (int i = 0; i < A; ++i) which[i] = -1e11;
	for (int i = 0; i < k; ++i) {
		char t;
		int v;
		scanf(" %c%d", &t, &v);
		which[t - 'A'] = v;
	}
	for (int i = 2; i <= n; ++i) if (n % i == 0) {
		p = i;
		break;
	}
	debug imie(p);
	auto r = run(word);
	ll ans = -llinf;
	for (int i = 0; i <= A; ++i) maxi(ans, r[i]);
	printf("%lld\n", ans);
}