#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

// using mint = modint998244353;
using mint = modint1000000007;
// using mint = modint;

void debug_mint1(vector<mint> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        cerr << vec[i].val() << " ";
    }
    cerr << endl;
}

void debug_mint2(vector<vector<mint>> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        for (int j = 0; j < vec[i].size(); j++) {
            cerr << vec[i][j].val() << " ";
        }
        cerr << endl;
    }
}

int main() {
    ll N;
    cin >> N;
    vector<ll> A(N);
    for (ll i = 0; i < N; i++){
        cin >> A[i];
    }
    A.push_back(0);
    string S;
    cin >> S;

    // その次の要素がどこにあるか？　を、前計算しておく
    vector<vector<ll>> next(N, vector<ll>(26, N));
    for (ll i = N - 1; i >= 0; i--){
        next[i][(ll)(S[i] - 'a')] = i;
        if (i < N - 1){
            for (ll j = 0; j < 26; j++){
                next[i][j] = min(next[i][j], next[i + 1][j]);
            }
        }
    }
    // debug(next);
    // 部分列 dp。ただし、その単位を最後まで使い切らなかった場合は同じ文字へは遷移不可とする
    vector<mint> dp1(N + 1, mint(0));
    vector<mint> dp2(N + 1, mint(0));
    dp1[0] = mint(1);

    for (ll i = 0; i < N; i++){
        for (ll j = 0; j < 26; j++){
            if (i > 0 && (ll)(S[i - 1] - 'a') == j){
                if (next[i][j] == N){
                    continue;
                }
                mint nxt = mint(A[next[i][j]]);
                dp1[next[i][j] + 1] += dp1[i];
                dp2[next[i][j] + 1] += (nxt - 1) * dp1[i];
            }
            else{
                if (next[i][j] == N){
                    continue;
                }
                mint nxt = A[next[i][j]];
                dp1[next[i][j] + 1] += dp1[i];
                dp2[next[i][j] + 1] += (nxt - 1) * dp1[i];
                dp1[next[i][j] + 1] += dp2[i];
                dp2[next[i][j] + 1] += (nxt - 1) * dp2[i];
            }
        }
    }
    mint ans = mint(0);
    for (ll i = 1; i <= N; i++){
        ans += dp1[i];
        ans += dp2[i];
    }
    cout << ans.val() << endl;
}