#include <bits/stdc++.h>
using namespace std;

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return vector(arg, init);
    else return vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename Container>
auto distance(const Container &c, decltype(begin(c)) iter) {
    return distance(begin(c), iter);
}

template <typename RIter, typename Compare = less<typename iterator_traits<RIter>::value_type>>
auto isort(RIter first, RIter last, Compare comp = Compare()) {
    vector<int> i(distance(first, last));
    iota(begin(i), end(i), 0);
    sort(begin(i), end(i), [&](auto x, auto y) {
        return comp(*(first + x), *(first + y));
    });
    return i;
}

template <typename, template <typename> typename, typename = void_t<>>
struct detect : false_type {};
template <typename T, template <typename> typename Check>
struct detect<T, Check, void_t<Check<T>>> : true_type {};
template <typename T, template <typename> typename Check>
constexpr inline bool detect_v = detect<T, Check>::value;

template <typename T>
using has_member_sort = decltype(declval<T>().sort());

template <typename Container, typename Compare = less<typename Container::value_type>>
auto sorted(Container c, Compare comp = Compare()) {
    if constexpr (detect_v<Container, has_member_sort>) {
        c.sort(comp);
        return c;
    }
    else {
        sort(begin(c), end(c), comp);
        return c;
    }
}

template <typename Container, typename Compare = equal_to<typename Container::value_type>>
auto uniqued(Container c, Compare comp = Compare()) {
    c.erase(unique(begin(c), end(c), comp), end(c));
    return c;
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

#include <atcoder/modint>
using mint = atcoder::modint1000000007;

int main() {
    constexpr int alpha = 'z' - 'a' + 1;

    auto ctoi = [](char c) -> int {
        return c - 'a';
    };

    int n; cin >> n;
    auto a = vec<int>(uns, n);
    for (auto &e : a) cin >> e;
    string s; cin >> s;

    auto dp = vec<mint>(uns, n + 1);

    dp[0] = 1;

    array<int, alpha> last = {};

    fill(begin(last), end(last), -1);
    for (int i = 1; i <= n; ++i) {
        mint other = dp[0];

        for (int j = 0; j < alpha; ++j) {
            if (last[j] < 0 || j == ctoi(s[i - 1])) {
                continue;
            }
            other += dp[last[j]];
        }

        dp[i] = other;
        if (0 <= last[ctoi(s[i - 1])]) {
            dp[i] += dp[last[ctoi(s[i - 1])]];
        }
        dp[i] += (a[i - 1] - 1) * other;

        last[ctoi(s[i - 1])] = i;
    }

    mint ans = 0;
    for (auto v : last) {
        if (0 <= v) {
            ans += dp[v];
        }
    }

    cout << ans.val() << endl;
}