#include <iostream>
#include <vector>
#include <string>
#include <optional>
#include <stdexcept>
#include <sstream>
#include <chrono>
#include <cstdlib> //rand()を使うために必要
#include <time.h>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>

using namespace std;

template <typename T>
bool next_combination(const T first, const T last, int k)
{
    const T subset = first + k;
    // empty container | k = 0 | k == n
    if (first == last || first == subset || last == subset)
    {
        return false;
    }
    T src = subset;
    while (first != src)
    {
        src--;
        if (*src < *(last - 1))
        {
            T dest = subset;
            while (*src >= *dest)
            {
                dest++;
            }
            iter_swap(src, dest);
            std::rotate(src + 1, dest + 1, last);
            std::rotate(subset, subset + (last - dest) - 1, last);
            return true;
        }
    }
    // restore
    std::rotate(first, subset, last);
    return false;
}

void solve()
{
    int N;
    string S;
    cin >> N >> S;
    vector<int> vec_s;
    for (int i = 0; i < N; i++)
        vec_s.push_back(i);
    int ans = 0;

    if (N < 5)
    {
        cout << 0 << endl;
        return;
    }

    do
    {
        set<char> char_set;
        for (int j = 0; j < 5; j++)
        {
            char_set.insert(S[vec_s[j]]);
        }
        if (S[vec_s[0]] == S[vec_s[2]] && char_set.size() == 4)
            ans++;
    } while (next_combination(vec_s.begin(), vec_s.end(), 5));
    cout << ans << endl;
}

void check_sw()
{
    // cout << "評価値算出=" << get_sum_time(eval_calculation_sw) / cnt_eval << endl;
}

int main()
{
    solve();
    // test();
    // check_sw();
}