#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

struct adat
{
	char ekat;
	int kmax = 0;
};

int main()
{
	ios::sync_with_stdio(false);
	int N;
	string s;
	int kszam;
	cin >> N >> s >> kszam;
	int pizzo[26];
	int mkatv = -1;
	for (int i = 0; i < kszam; i++)
	{
		char c;
		int v;
		cin >> c >> v;
		pizzo[c - 'A'] = v;
		if (v > mkatv)
			mkatv = v;
	}
	vector<adat> a(N);
	for (int i = 0; i < N; i++)
	{
		a[i].ekat = s[i];
		if (s[i] == '?')
		{
			a[i].kmax = mkatv;
		}
		else
		{
			a[i].kmax = pizzo[s[i] - 'A'];
		}
	}
	if (N == 1)
	{
		cout << a[0].kmax << "\n";
		return 0;
	}
	int p = 2;
	while (N % p != 0)
		p++;
	int szint = 1;
	while (a.size() > 1)
	{
		szint++;
		vector<adat> ea(a.size() / p);
		swap(a, ea);
		for (size_t i = 0; i < a.size(); i++)
		{
			adat& A = a[i];
			A.ekat = '?';
			int u = 0;
			for (int j = 0; j < p; j++)
			{
				adat eA = ea[i + j * a.size()];
				A.kmax += eA.kmax;
				if(A.ekat == '?')
					A.ekat = eA.ekat;
				else if (eA.ekat == '.' || eA.ekat != '?' && eA.ekat != A.ekat)
					A.ekat = '.';
			}
			if (A.ekat != '.')
			{
				A.kmax = max(A.kmax, N / (int)a.size() * szint * (A.ekat != '?' ? pizzo[A.ekat - 'A'] : mkatv));
			}
		}
	}
	cout << a[0].kmax << "\n";
}