#include <bits/stdc++.h>
using namespace std;
#define int long long
const int mod = 1e9 + 7;
signed main()
{
    int n, c = 1;
    string s;
    cin >> n >> s;
    for (char i = 'a'; i <= 'z'; i++)
        (c *= count(s.begin(), s.end(), i) + 1) %= mod;
    cout << c - 1 << endl;
    return 0;
}