#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
using Graph = vector<vector<int>>;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define NP next_permutation
const int INF32 = 2e9;
const ll INF64 = 2e18;
const ll mod = 998244353;
// const ll mod = 1e9 + 7;
template<typename T> bool chmin(T &a, T b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T &a, T b){if(a < b){a = b; return true;} return false;}
 
void cincout() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
}
 
int main() {
    cincout();
 
    int N;
    string S;
    cin >> N >> S;

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

    vector<int> P(N);
    for (int i = 0; i < 5; i++) P[i] = 1;
    sort(all(P));

    int ans = 0;
    do {
        string T;
        for (int i = 0; i < N; i++) if (P[i]) T += S[i];

        bool ok = true;
        for (int i = 0; i < 5; i++) {
            for (int j = i + 1; j < 5; j++) {
                if (i == 0 && j == 2) continue;
                
                if (T[i] == T[j]) ok = false;
            }
        }

        if (ok && T[0] == T[2]) ans++;
    } while (NP(all(P)));

    cout << ans << endl;
}