#include <bits/stdc++.h>
#define FOR(i, n) for(int i = 0; i < (n); ++i)
#define REP(i, a, b) for(int i = (a); i < (b); ++i)
#define TRAV(i, a) for(auto & i : (a))
#define SZ(x) ((int)(x).size())
#define X first
#define Y second
#define PR std::pair
#define MP std::make_pair
typedef long long ll;
typedef std::pair<int, int> PII;
typedef std::vector<int> VI;

int cost[266];
std::vector<char> chars;
int BEST;

ll rec(std::string s, int p, int ile);

ll podziel(std::string s, int p, int ile){
    ll ret = 0;
    FOR(kt, p){
        std::string heh;
        for(int i = kt; i < SZ(s); i += p){
            heh += s[i];
        }
        ret += rec(heh, p, ile-1);
    }
    return ret;
}



ll rec(std::string s, int p, int ile){
    char moj = s[0];
    bool bad = false;
    TRAV(c, s){
        if(c != '?' && c != moj){
            bad = true;
        }
    }

    // std::cout << "rec " << s << " " << p << " " << ile << std::endl;

    if(bad) return podziel(s, p, ile);

    ll cand = 0;
    if(ile > 1){
        cand = podziel(s, p, ile);
    }

    if(moj == '?'){
        // std::cout << "ret " << std::max(cand, 1ll * BEST * SZ(s) * ile) << std::endl;
        return std::max(cand, 1ll * BEST * SZ(s) * ile);
    }else{
        // std::cout << "ret " << std::max(cand, 1ll * cost[moj] * SZ(s) * ile) << std::endl;
        return std::max(cand, 1ll * cost[moj] * SZ(s) * ile);
    }
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(0);

    int n;
    std::cin >> n;
    std::string s;
    std::cin >> s;

    int k;
    std::cin >> k;
    FOR(i, k){
        char a;
        int b;
        std::cin >> a >> b;
        chars.push_back(a);
        cost[a] = b;
        BEST = std::max(BEST, b);
    }

    int p = 1;
    REP(i, 2, n+1){
        if(n % i == 0){
            p = i;
            break;
        }
    }

    int ile = 1;
    int cp = n;
    while(cp != 1){
        cp /= p;
        ile++;
    }

    std::cout << rec(s, p, ile) << "\n";

    return 0;
}