/*  This Code is Submitted by wywcgs for Problem 2333 on 2006-08-25 at 17:08:07 */ 
#include <cstdio>
#include <algorithm>
using namespace std;

const char TN[] = "22233344455566677778889999";
const char TT[] = "12312312312312312341231234";
const int L = 1024;

int tp(char);
int tt(char);

int main()
{
	int T, a, b;
	char w[L];
	
	scanf("%d", &T);
	for(int t = 0; t < T; t++) {
		scanf("%d %d\n", &a, &b);
		int total = 0;
		gets(w);
		for(int i = 0; w[i] != 0; i++) {
			total += tt(w[i])*a;
			if(i != 0 && tp(w[i-1]) == tp(w[i]) && w[i] != ' ') total += b;
		}
		printf("%d\n", total);
	}	
	
	return 0;
}

int tp(char c)
{
	if(c == ' ') return 1;
	else return TN[c-'A']-'0';
}
int tt(char c)
{
	if(c == ' ') return 1;
	else return TT[c-'A']-'0';
}