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

lld val[26];

lld sol(const string& s, lld p) {
	if(s.length() == 1)
		return (s[0] == '?' ? *max_element(val,val+26) : val[s[0]-'A']);

	lld res = 0;
	for(int i=0;i<26;i++) {
		bool ok = true;
		for(char c : s)
			if(!(c == '?' || c == 'A'+i)){ ok = false; break; }

		if(ok) {
			lld sum = 0;
			int n = s.length();
			while(n > 0) sum += (lld) s.length() * val[i], n /= p;
			res = max(res, sum);
		}
	}

	lld sum = 0;
	vector<string> t(p,"");
	for(int i=0;i<s.length();i++)
		t[i%p] += s[i];

	for(auto& i : t)
		sum += sol(i,p);

	return max(sum,res);
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);

	lld n;
	string s;
	cin >> n >> s;

	lld k;
	cin >> k;
	for(lld i=0;i<k;i++) {
		char a;
		lld b;
		cin >> a >> b;
		val[a-'A'] = b;
	}

	lld p = 2;
	if(n == 1)
		p = 1;
	else
		while(n%p != 0) p++;

	cout << sol(s,p) << "\n";

	return 0;
}