#include <stdio.h>

const int Mod = 1000000007;

void add_BIT(int N, long long BIT[], int i, int k)
{
	while (i <= N) {
		BIT[i] += k;
		i += (i & -i);
	}
}

long long sum_BIT(long long BIT[], int r)
{
	long long sum = 0;
	while (r > 0) {
		sum += BIT[r];
		r -= (r & -r);
	}
	return sum;
}

int main()
{
	int i, N, A[200001];
	char S[200003];
	scanf("%d", &N);
	for (i = 1; i <= N; i++) scanf("%d", &(A[i]));
	scanf("%s", &(S[1]));
	
	int last[26] = {}, dp[200001];
	long long BIT[200001] = {};
	long long ans = 0;
	for (i = 1, dp[0] = 1; i <= N; i++) {
		dp[i] = (sum_BIT(BIT, i - 1) - sum_BIT(BIT, last[S[i] - 'a']) + dp[last[S[i] - 'a']]) % Mod;
		last[S[i] - 'a'] = i;
		ans += (long long)dp[i] * A[i] % Mod;
		add_BIT(N, BIT, i, (long long)dp[i] * A[i] % Mod);
	}
	printf("%lld\n", ans % Mod);
	fflush(stdout);
	return 0;
}