#include <iostream>
#include <vector>

using namespace std;

const int MAXN = 100'001;
const int MAXE = 20;

string s[MAXE];
long long val[128];
vector<long long> dp[MAXE];

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

    int n, p, e, k;

    cin>>n;

    if (n == 1) {
        p = 1;
        e = 0;
    } else {
        for (p = 2; p * p <= n && n % p; ++p);
        if (p * p > n) p = n;
        e = 1;
        for (int x = p; x != n; x *= p, ++e);
    }

    cin>>s[e]>>k;

    for (int i = 0; i < k; ++i) {
        char c;
        cin>>c;
        cin>>val[c];
        val['?'] = max(val['?'], val[c]);
    }

    dp[e].resize(n);
    for (int i = 0; i < n; ++i) {
        dp[e][i] = val[s[e][i]];
    }

    for (int i = e - 1, step = n / p, sz = p, prv = n; i >= 0; --i, prv = step, step /= p, sz *= p) {
        s[i].resize(step, '?');
        dp[i].resize(step);

        for (int j = 0; j < step; ++j) {
            for (int k = j; k < prv; k += step) {
                if (s[i + 1][k] != '?') {
                    if (s[i][j] == '?') s[i][j] = s[i + 1][k];
                    else if (s[i][j] != s[i + 1][k]) s[i][j] = '!';
                }
                dp[i][j] += dp[i + 1][k];
            }
            dp[i][j] = max(dp[i][j], val[s[i][j]] * (e - i + 1) * sz);
        }
    }

    cout<<dp[0][0]<<'\n';
}