#include <iostream>
#include <string>
#include <set>
using namespace std;

bool is_cpctf_like(string s) {
    if (s[0] != s[2]) return false;

    set<char> chars;
    for (int i = 0; i < 5; ++i) chars.insert(s[i]);

    if (chars.size() != 4) return false;

    int count[26] = {0};
    for (char c : s) count[c - 'A']++;

    return count[s[0] - 'A'] == 2;
}

int main() {
    int N;
    string S;
    cin >> N >> S;

    int count = 0;
    for (int i = 0; i < N; ++i)
        for (int j = i + 1; j < N; ++j)
            for (int k = j + 1; k < N; ++k)
                for (int l = k + 1; l < N; ++l)
                    for (int m = l + 1; m < N; ++m) {
                        string sub = {S[i], S[j], S[k], S[l], S[m]};
                        if (is_cpctf_like(sub)) {
                            count++;
                        }
                    }

    cout << count << endl;
    return 0;
}