#include <iostream>
#include <vector>
// #include "../Kody/simple-console-debug/debug.h"
using namespace std;

int n,k,p;
string init_state;
vector<int>V(1000);
int best_letter_val;

//get best partial solution
long long R(int start, int jump, int alpha, int current_n){
    // deb::Indent ind;
    // cerr << ind.head << "R(start=" << start << " jump=" << jump << " alpha=" << alpha << " current_n=" << current_n << endl;
    //edge case
    if(alpha==0)
        return init_state[start]=='?' ? best_letter_val : V[init_state[start]];

    //check if possible all equal
    char the_one = '?';
    for(int i=start;;){
        if(init_state[i]!='?'){
            if(the_one=='?')
                the_one = init_state[i];
            else if(the_one!=init_state[i]){
                the_one = '!';
                break;
            }
        }

        i=(i+jump)%n;
        if(i==start)
            break;
    }

    // cerr << ind << "the_one=" << the_one << endl;

    long long sol1 = 0;
    if(the_one!='!'){
        long long val = (the_one=='?') ? best_letter_val : V[the_one];
        sol1 = val*(alpha+1)*current_n;
    }

    //check without this assumption
    long long sol2 = 0;
    for(int i=0;i<p;i++)
        sol2 += R(start + jump*i, jump*p, alpha-1, n/p);

    // cerr << ind << "sol1=" << sol1 << " sol2=" << sol2 << endl;
    return max(sol1, sol2);
}

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

    cin >> n >> init_state >> k;

    best_letter_val = -1;
    for(int i=0;i<k;i++){
        string s;
        int v;
        cin >> s >> v;
        V[s[0]] = v;
        best_letter_val = max(best_letter_val, v);
    }

    //get p
    int alpha;

    if(n==1){
        p=2; alpha=0;
    }
    else{
        for(p=2;n%p;p++);
        alpha=0;
        for(int nn=n;nn>1;nn/=p,alpha++);
    }

    cout << R(0, 1, alpha, n) << "\n";

    return 0;
}