#include <bits/stdc++.h>

#define endl '\n'
#define DEBUG_VAR(x) { cerr << "* "x" = " << x << endl; }
#define DEBUG_FMT(...) { cerr << "* "; fprintf(stderr, __VA_ARGS__); }

using namespace std;
using LL = long long;

int n;
int p, m; // n = p^m

string str;

int all;
LL v[26];
LL maxv;

LL solve(int pos, int t)
{
	if(t == m) {
		if(str[pos] == '?') return maxv;
		else return v[str[pos]-'A'];
	}

	int step = 1;
	for(int i = 1; i <= t; i++) 
		step *= p;

	bool flag = true;
	char curC = 'A'-1;
	bool hasTwoC = false;
	for(int i = pos; i != pos || flag; i = (i+step)%n) {
		flag = false;
		if(str[i] == '?') continue;
		else {
			if(curC == 'A'-1) {
				curC = str[i];
			} else if(str[i] != curC) {
				hasTwoC = true;
			}
		}
	}

	LL res = 0;
	if(curC == 'A'-1) { // all ?
		res = (n/step)*maxv*(m-t+1);
	} else if(hasTwoC) {
		res = 0;
	} else {
		res = (n/step)*v[curC-'A']*(m-t+1);
	}

	// DEBUG_FMT("solve(pos = %d, t = %d): res = %lld, step = %d\n", pos, t, res, step);

	LL temp = 0;
	for(int j = 0, i = pos; j < p; j++, i = (i+step)%n) {
		temp += solve(i, t+1);
	}

	return max(temp, res);
}

int main()
{
	freopen("1.in", "r", stdin);
	ios::sync_with_stdio(false); cin.tie(nullptr);

	cin >> n;
	p = 2;
	while(n%p) p++;
	int temp = n;
	while(temp > 1 && temp%p == 0) {
		temp /= p;
		m++;
	}

	cin >> str;

	cin >> all;
	for(int i = 1; i <= all; i++) {
		char c; cin >> c;
		cin >> v[c-'A'];
		maxv = max(maxv, v[c-'A']);
	}

	cout << solve(0, 0) << endl;

	return 0;
}