#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;
using pii = pair<int,int>;
using graph = vector<vi>;

#define FOR(name__, upper__) for (int name__ = 0; name__ < (upper__); ++name__)
#define all(x) begin(x), end(x)
#define mp make_pair
#define mt make_tuple

template<class T>
void initialize_matrix(vector<vector<T>>& matrix, int rows, int cols, T value) {
	assert(matrix.empty());
	FOR (row, rows) 
		matrix.emplace_back(cols, value);
}

void get_prime_power(ll n, ll &p, ll &x) {
	for (p = 2; p <= n; p++) {
		if (n % p == 0) break;
	}
	
	ll a = p;
	x = 1;
	while (a < n) a *= p, x++;
}

ll find_best(const string& s, const vector<ll>& cost, ll n, int index, ll jump_len, ll p, ll x) {
	if (x < 0) return 0;
	
	char change_letter = s[index];
	for (int i = index; i < n; i += jump_len) {
		if (s[i] != change_letter) {
			if (s[i] == '?') continue;
			else if (change_letter == '?') change_letter = s[i]; 
			else change_letter = 0;
		}
	}
	

	ll split_cost = 0;
	
	/*
	int i = index;
	FOR (_, p) {
		split_cost += find_best(s, cost, n, i, jump_len * p, p, x - 1);
		i += jump_len;
	}
	*/
	for (int i = index; i < index + p; i++) { 
		split_cost += find_best(s, cost, n, i, jump_len * p, p, x - 1);
	}
	

	//std::cout << "index: " << index << ", jump_len = " << jump_len << ", x = " << x << ", change_letter = " << change_letter << std::endl;
	ll quantity = n / jump_len;

	// we can get anything
	if (change_letter == '?') {
		ll best_cost = *std::max_element(cost.begin(), cost.end()) * quantity * (x + 1);
		return best_cost;
	}
	// we can get anything selected 
	else if (change_letter == 0) {
		return split_cost;
	}
	// one custom letter
	else {
		ll letter_cost = cost[change_letter - 'A'] * quantity * (x + 1);
		return std::max(letter_cost, split_cost);
	}
}


void go() {
	ll n; string s;
	
	cin >> n >> s;
	
	vector<ll> cost(30, 0);
	
	ll q; cin >> q;
	while (q--) {
		char a; ll c;
		cin >> a >> c;
		cost[a - 'A'] = c;
	}
	
	ll p, x;
	get_prime_power(n, p, x);
	
	cout << find_best(s, cost, n, 0, 1, p, x) << endl;
}

int main() {
	ios::sync_with_stdio(false); 
	cin.tie(0);

	go();

	return 0;
}