#include <bits/stdc++.h>

using namespace std;

#define ALL(x) (x).begin(), (x).end()

template<class C> void mini(C &a5, C b5) { a5 = min(a5, b5); }
template<class C> void maxi(C &a5, C b5) { a5 = max(a5, b5); }

#ifdef LOCAL
const bool debug = true;
#else
const bool debug = false;
#define cerr if (true) {} else cout
#endif

#define int long long
#define double long double

const int INF = 1e18;
const int mod = 1e9 + 7;

string substr(const string &s, int pocz, int step) {
	string res;
	for (int i = pocz; i < (int)s.size(); i += step) {
		res.push_back(s[i]);
	}
	return res;
}

int cost[1010];

int solve(const string &s, int p, int k) {
	cerr << s << " " << p << " " << k << endl;
	char lit = '?';
	bool good = true;
	for (char c : s) {
		if (c != '?') {
			if (lit == '?') {
				lit = c;
			} else if (lit != c) {
				good = false;
			}
		}
	}
	
	int res = 0;
	if ((int)s.size() > 1) {
		for (int i = 0; i < p; i++) {
			res += solve(substr(s, i, p), p, k - 1);
		}
	}
	
	if (good) {
		maxi(res, (int)s.size() * cost[(int)lit] * (k + 1));
	}
	return res;
}

int pot(int n, int k) {
	int res = 1;
	while (k--) {
		res *= n;
	}
	return res;
}

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    int n;
    cin >> n;
    string s;
    cin >> s;
    
    int k;
    cin >> k;
    int ma = 0;
    for (int i = 0; i < k; i++) {
		char c; int a;
		cin >> c >> a;
		cost[(int)c] = a;
		maxi(ma, a);
	}
	cost[(int)'?'] = ma;
	
	int p = 2;
	while (n % p) p++;
	k = 1;
	while (pot(p, k) < n) k++;
	
	cerr << "p k " << p << " " << k << endl;
	cout << solve(s, p, k) << "\n";
    
    return 0;
}/*
4
A?A?
2
A 10
B 25

4
A??A
2
A 10
B 25

4
A?B?
2
A 10
B 25
*/