#include<bits/stdc++.h>
using namespace std;
#ifdef DEB
#define D if(1)
#else
#define D if(0)
#endif

#define fo(a,b) for(int a=0;a<(b);++a)
using ll = long long;

const int KMAX = 27;
const int NMAX = 212345;
int n, k;
ll money[KMAX];
ll opt_money;
char in[NMAX];


struct Node
{
	char inside = 0;
	ll val ;
	ll val_nogar;
	int size = 0;
};



Node dp[NMAX];

#define NOPE (-(1ll<<40))


void prline(int i)
{
	printf("%d [%lld %lld] %d\n", dp[i].inside, dp[i].val, dp[i].val_nogar, dp[i].size);
}


int main(int argc, char ** argv)
{
	scanf("%d %s",&n,in);
	scanf("%d",&k);
	fo(i,k)
	{
		char c;
		ll val;
		scanf(" %c %lld", &c, &val);
		money[c-'A'+1]=val;
		opt_money = max(opt_money, val);
	}
	fo(i,n) in[i] = in[i]=='?'?0:in[i]-'A'+1;

	int p;
	for(p=2;n%p;p++);

	fo(i,n)
	{
			dp[i].inside = in[i];
			dp[i].size = 1;
			if(in[i])
			{
				dp[i].val = money[in[i]];
				dp[i].val_nogar = money[in[i]];
			}
			else
			{
				dp[i].val = opt_money;
				dp[i].val_nogar = opt_money;
			}
	}

	int start = n;
	int old_start = 0;
	int jump = n/p;
	int count = p;

	for(;jump; jump/=p, count*=p)
	{
		D printf("-----------------\n");
		fo(i, jump)
		{
			Node & out = dp[start+i];
			fo(j,p)
			{
				Node & act = dp[old_start+i+j*jump];
				out.size += act.size;
				out.val_nogar += act.val_nogar;
				if(!out.inside) out.inside = act.inside;
				if(act.inside && out.inside && out.inside!=act.inside)
					out.inside = 100;
			}
			out.size+=count;
			if(!out.inside)
				out.val = out.size * opt_money;
			else if(out.inside == 100)
				out.val = 0;
			else
				out.val = out.size * money[out.inside];
			out.val_nogar = max(out.val, out.val_nogar);
			D prline(start+i);
		}
		old_start = start;
		start += jump;
	}

	printf("%lld\n",dp[old_start].val_nogar);



	return 0;
}