import java.io.*;
import java.util.*;

public class n1{
	public static int[] solve(int a){
		if(a==1){
			return new int[]{1,1};
		}
		for(int i=2;i<=a;i++){
			if(a%i==0){
				int count=0;
				while(a>1){
					a/=i;
					count++;
				}
				return new int[]{i,count};
			}
		}
		System.out.println("ERROR");
		return null;
	}
	static int p;
	static int n;
	static int bestValue;
	public static void main(String[] args) throws Exception{
		int i=I.readInt();
		int[] q=solve(i);
		p=q[0];
		n=q[1];
		String s=I.readLine();
		int[] values=new int[26];
		int c=I.readInt();
		for(int ii=0;ii<c;ii++){
			char cc=I.readString().charAt(0);
			values[cc-'A']=I.readInt();
		}
		int[] ss=new int[s.length()];
		for(int ii=0;ii<s.length();ii++){
			ss[ii]=s.charAt(ii)=='?'?-1:s.charAt(ii)-'A';
		}
		solve(ss,values);
	}
	public static int max(int[]q) {
		int m=0;
		for(int i:q) {
			m=Math.max(i,m);
		}
		return m;
	}
	private static void solve(int[] id,int[] values){
//		System.out.println(Arrays.toString(id));
//		System.out.println(Arrays.toString(values));
		bestValue=max(values);
		int ans=solveAux(id, values, 0, 1, 0);
		System.out.println(ans);
	}
	public static int solveAux(int[]id, int[]values, int offset, int skip, int pow) {
		if(pow==n) {
			if(id[offset]==-1) {
				return bestValue;
			}else {
				return values[id[offset]];
			}
		}
		//Can every element be the same?
		int must=-1;
		boolean ok=true;
		for(int i=offset;i<id.length;i+=skip) {
			if(id[i]>=0) {
				if(must==-1) {
					must=id[i];
				}else if(id[i]!=must){
					ok=false;
					break;
				}
			}
		}
		int valueAll=0;
		if(ok) {
			int val=bestValue;
			if(must!=-1) {
				val=values[must];
			}
			valueAll = val*id.length/skip*(n+1-pow);
		}
		// Solve problems below instead
		int valueSplit = 0;
		for(int i=0;i<p;i++) {
			int offset2 = offset+i*skip;
			int skip2=skip*p;
			int pow2=pow+1;
			valueSplit+=solveAux(id, values, offset2, skip2, pow2);
		}
		int ans=Math.max(valueAll,valueSplit);
		return ans;
	}
}

class I{
	static BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
	static StringTokenizer st;

	public static String nextToken() throws Exception{
		while(st==null||!st.hasMoreTokens()){
			st=new StringTokenizer(in.readLine(),"[ ,:]");
		}
		return st.nextToken();
	}

	public static int readInt() throws Exception{
		return Integer.parseInt(nextToken());
	}

	public static long readLong() throws Exception{
		return Long.parseLong(nextToken());
	}

	public static double readDouble() throws Exception{
		return Double.parseDouble(nextToken());
	}

	public static String readString() throws Exception{
		return nextToken();
	}

	public static String readLine() throws Exception{
		return in.readLine();
	}
}