#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main () {
    int N;
    cin >> N;
    ll num[200010];
    for (int i = 0; i < N; i ++) {
        cin >> num[i];
    }
    string s;
    cin >> s;
    int id[26];
    ll dp[26];
    for (int i = 0; i < 26; i ++) {
        id[i] = -1;
        dp[i] = 1;
    }
    ll m = 1e9 + 7;
    ll ans = num[0];
    for (int i = 0; i < N; i ++) {
        int n = s[i] - 'a';
        for (int j = 0; j < 26; j ++) {
            if (j != n && id[j] > id[n]) {
                dp[n] += (dp[j] * num[id[j]]) % m;
                dp[n] %= m;
            }
        }
        id[n] = i;
        ans += (dp[n] * num[i]) % m;
        ans %= m;
    }
    cout << ans << endl;
}