#include <cstdio>
#include <algorithm>
using namespace std;
typedef long long ll;
constexpr int MAXN = 100'005;

int n;
int prime;
char s[MAXN];
int pizzo[100];
int maxpizzo = 0;

ll util(const int x, const int d)
{
	if (d == n)
		return pizzo[s[x]];

	ll ans = 0;
	for (int i = 0; i < prime; i++)
		ans += util((x + i * d) % n, d * prime);

	const int elems = n / d;
	char cchar = 0;
	for (int i = 0; i < elems; i++)
	{
		const char c = s[(x + i * d) % n];
		if (c == '?')
			;
		else if (cchar == 0)
			cchar = c;
		else if (c != cchar)
			cchar = '!';
	}

	int val = 0;
	if (cchar == 0)
		val = maxpizzo;
	else if (cchar != '!')
		val = pizzo[cchar];

	int e = 0;
	for (int i = d; i <= n; i *= prime)
		e += elems;

	ll ans2 = (ll)val * e;
	return max(ans, ans2);
}

int main()
{
	int n, k;
	scanf("%d %s %d", &n, s, &k);
	::n = n;
	for (int i = 0; i < k; i++)
	{
		char c;
		int v;
		scanf(" %c %d ", &c, &v);
		pizzo[c] = v;
		maxpizzo = max(maxpizzo, v);
	}
	pizzo['?'] = maxpizzo;

	for (int i = 2; i < n; i++)
		if (n % i == 0)
		{
			prime = i;
			break;
		}

	printf("%lld\n", util(0, 1));
	return 0;
}