#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic pop
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) { a = max(a, b); }
template<class T> void chmin(T& a, const T& b) { a = min(a, b); }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint1000000007;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  VI a(n);
  rep(i, n) cin >> a[i];
  string s;
  cin >> s;
  int last_pos[26];
  rep(i, 26) last_pos[i] = -1;
  fenwick_tree<mint> ft(n + 1);
  ft.add(0, 1);
  rep(i, n) {
    int x = s[i] - 'a';
    int c = a[i];
    mint v = ft.sum(last_pos[x] + 1, n + 1);
    ft.add(i, (c - 1) * v);
    ft.add(i + 1, v);
    last_pos[x] = i;
  }
  mint ans = ft.sum(0, n + 1) - 1;
  cout << ans.val() << '\n';
}