#include<stdio.h>
int main()
{
	int n;
	scanf("%d", &n);
	char s[200005];
	scanf("%s", s);
	int i;
	long long int a[200005];
	for (i = 0; i < n; i++)
		scanf("%lld", &a[i]);
	for (i = 0; i < n; i++)
		if (s[i] == 'B')
			a[i] *= -1;
	long long int ans, min, max, sum;
	ans = min = max = sum = 0;
	for (i = 0; i < n; i++)
	{
		sum += a[i];
		if (ans < max - sum)
			ans = max - sum;
		if (ans < sum - min)
			ans = sum - min;
		if (max < sum)
			max = sum;
		if (sum < min)
			min = sum;
	}
	printf("%lld\n", ans);
	return 0;
}