#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using Mint = atcoder::modint1000000007;

int main()
{
    int N;
    cin >> N;
    vector<int> A(N);
    for (int &a : A)
        cin >> a;
    string s;
    cin >> s;
    vector<Mint> lst(26);
    Mint pre = 1;
    for (int i = 0; i < N; i++)
    {
        Mint pp = pre;
        Mint ref = lst[s[i] - 'a'];
        pre = (A[i] + 1) * pp - A[i] * ref;
        lst[s[i] - 'a'] = A[i] * pp - (A[i] - 1) * ref;
    }
    cout << (pre - 1).val() << endl;
}