#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using ll   = long long;
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define reps(i, a, b) for (ll i = (a); i < (b); i++)
bool chmin(auto &a, auto b) { return a > b ? a = b, 1 : 0; }
bool chmax(auto &a, auto b) { return a < b ? a = b, 1 : 0; }
vector<ll> sin45 = {0, 1, 1, 1, 0, -1, -1, -1}, cos45 = {1, 1, 0, -1, -1, -1, 0, 1};
vector<ll> dx = {0, 1, 0, -1};
vector<ll> dy = {1, 0, -1, 0};
#define ft first
#define sd second
#define all(x) std::begin(x), std::end(x)
#define mp(a, b) make_pair(a, b)
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb(x) push_back(x)
#define so(z) sort(z.begin(), z.end())
#define sor(z) sort(z.rbegin(), z.rend())
#define vec vector<ll>
#define vecc vector<vector<ll>>

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    ll n;
    string s;
    cin >> n >> s;

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

    vector<int> mask(n, 0);

    rep(i, 5) mask[i] = 1;
    sort(mask.begin(), mask.end());

    ll ans = 0;

    do {
        string t;
        rep(i, n) {
            if (mask[i] == 1) t += s[i];
        }

        bool flag = true;

        set<char> st;
        for (auto c : t) { st.insert(c); }
        if (st.size() != 4) flag = false;

        if (t[0] != t[2]) flag = false;

        if (flag) ans++;

    } while (next_permutation(mask.begin(), mask.end()));

    cout << ans << endl;
}