#include <bits/stdc++.h>
#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)
using namespace std;
using ll = long long;
template<typename T>
inline bool chmax(T& a, const T& b) {
    if (a < b){
        a = b;
        return true;
    }
    return false;
}
template<typename T>
inline bool chmin(T& a, const T& b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T> vector<T> make_vec(size_t n) { return vector<T>(n); }
template<typename T, typename... Args> auto make_vec(size_t n, Args... args) {
    return vector<decltype(make_vec<T>(args...))>(n, make_vec<T>(args...));
}
template<typename T, typename U, typename... V>
typename enable_if<is_same<T, U>::value>::type fill_v(U& u, const V... v) { u = U(v...); }
template<typename T, typename U, typename... V>
typename enable_if<!is_same<T, U>::value>::type fill_v(U& u, const V... v) {
    for (auto& e : u) fill_v<T>(e, v...);
}

template<uint_fast64_t Modulus>
struct modint {
    using u64 = uint_fast64_t;
    u64 a;
    constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
    constexpr u64& value() noexcept { return a; }
    constexpr const u64& value() const noexcept { return a; }
    constexpr modint operator+(const modint rhs) const noexcept {
        return modint(*this) += rhs;
    }
    constexpr modint operator-(const modint rhs) const noexcept {
        return modint(*this) -= rhs;
    }
    constexpr modint operator*(const modint rhs) const noexcept {
        return modint(*this) *= rhs;
    }
    constexpr modint operator/(const modint rhs) const noexcept {
        return modint(*this) /= rhs;
    }
    constexpr modint& operator+=(const modint rhs) noexcept {
        a += rhs.a;
        if (a >= Modulus) a -= Modulus;
        return *this;
    }
    constexpr modint& operator-=(const modint rhs) noexcept {
        if (a < rhs.a) a += Modulus;
        a -= rhs.a;
        return *this;
    }
    constexpr modint& operator*=(const modint rhs) noexcept {
        a = a * rhs.a % Modulus;
        return *this;
    }
    constexpr modint& operator/=(modint rhs) noexcept {
        return *this *= rhs.inv();
    }
    constexpr modint& operator++() noexcept {
        a++;
        if (a = Modulus) a = 0;
        return *this;
    }
    constexpr modint operator++(int) noexcept {
        modint tmp(*this);
        operator++();
        return tmp;
    }
    constexpr modint& operator--() noexcept {
        if (a == 0) a = Modulus;
        a--;
        return *this;
    }
    constexpr modint operator--(int) noexcept {
        modint tmp(*this);
        operator--();
        return tmp;
    }
    constexpr modint pow(u64 exp) const noexcept {
        modint res(1), mul(*this);
        for (; exp; mul *= mul, exp >>= 1) if (exp & 1) res *= mul;
        return res;
    }
    constexpr modint inv() const noexcept {
        return modint(*this).pow(Modulus - 2);
    }
};

using mint = modint<1000000007>;

ostream& operator<<(ostream&os, const mint& obj) { return os << obj.a; }
bool operator==(const mint& lhs, const mint& rhs) { return lhs.a == rhs.a; }
bool operator!=(const mint& lhs, const mint& rhs) { return !(lhs == rhs); }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    string s;
    cin >> n >> s;
    vector<int> cnt(26);
    rep(i, n) cnt[s[i] - 'a']++;

    mint ans = 1;
    rep(i, 26) ans *= cnt[i] + 1;
    ans--;
    cout << ans << '\n';
}


Measured memory_bytes: 3744