#include <cstdio>
#include <vector>
#include <iostream>
using namespace std;

const int mod = 1e9 + 7;

int main() {
	int n;
	scanf("%d", &n);
	vector<int> a(n + 1);
	for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
	vector<int> sum(n + 1, 0);
	vector<int> f(n + 1, 0);
	vector<int> lst(n + 1);
	string s;
	cin >> s;
	vector<int> pos(26, -1);
	for (int i = 1; i <= n; i++) {
		int u = s[i - 1] - 'a';
		lst[i] = pos[u];
		pos[u] = i;
	}
	
	auto seg = [&](int l, int r) {
		if (l > r) return 0;
		int res = sum[r];
		if (l - 1 >= 0) res -= sum[l - 1];
		if (res < 0) res += mod;
		return res;
	};
	
	int ans = 0;
	f[0] = 1;
	sum[0] = 1;
	vector<int> single(n + 1);
	for (int i = 1; i <= n; i++) {
		int cur = 0;
		if (lst[i] == -1) cur = seg(0, i - 1);
		else {
			cur = seg(lst[i] + 1, i - 1);
			cur = (cur + single[lst[i]]) % mod;
		}
		single[i] = cur;
		cur = cur * 1ll * a[i] % mod;
		// printf("i = %d, cur = %d\n", i, cur);
		sum[i] = (sum[i - 1] + cur) % mod;
		ans = (ans + cur) % mod;
	}
	printf("%d\n", ans);
	return 0;	
}