#include <bits/stdc++.h>

#include <atcoder/modint>
using namespace std;

using mint = atcoder::modint1000000007;

mint res;
int main() {
	int n;
	cin >> n;
	vector a(n, 0);
	for(auto &v : a) cin >> v;
	string s;
	cin >> s;
	vector dp(26, mint(0));
	for(int i = 0; i < n; i++) {
		mint x = (res - dp[s[i] - 'a'] + 1) * a[i];
		dp[s[i] - 'a'] += x;
		res += x;
	}
	cout << res.val() << '\n';
	return 0;
}