#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 = 30;
const int NMAX = 212345;
int n, k;
ll money[KMAX];
char in[NMAX];


ll dp[NMAX][KMAX];

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


void prline(int i)
{
	fo(x,KMAX) printf(dp[i][x]<0?"   N":" %3lld", dp[i][x]);
	printf("\n");
}


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;
	}
	fo(i,n) in[i] = in[i]=='?'?0:in[i]-'A'+1;

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

	fo(i,n)
	{
		fo(x,KMAX)
			if(!in[i] || in[i]==x)
				dp[i][x]=money[x];
			else
				dp[i][x]=NOPE;
		fo(x,KMAX) dp[i][0] = max(dp[i][0], dp[i][x]);
		D prline(i);
	}

	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)
		{
			fo(x, KMAX) 
				fo(j,p)
					dp[start+i][x] += dp[old_start+i+j*jump][x];
			fo(x, KMAX) if(x) dp[start+i][x] += count*money[x];
			fo(x,KMAX) dp[start+i][0] = max(dp[start+i][0], dp[start+i][x]);
			fo(x,KMAX) if(dp[start+i][x] < 0) dp[start+i][x] = NOPE;
			D prline(start+i);
		}
		old_start = start;
		start+= jump;
	}

	printf("%lld\n",dp[old_start][0]);



	return 0;
}