#include <bits/stdc++.h>
using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    string s; cin >> s;

    int answer = 0;
    string t = "AAAAA";
    while(true){
        if(t.at(0) == t.at(2)){
            int Se = 0;
            bool ok = true;
            for(int i=1; i<5; i++){
                int c = t.at(i)-'A';
                if(Se&(1<<c)){ok = false; break;}
                Se |= 1<<c;
            }
            if(ok){
                vector<int> dp(5);
                dp.at(0) = 1;
                for(auto c : s){
                    for(int i=4; i>=0; i--){
                        if(t.at(i) == c){
                            if(i == 4) answer += dp.at(i);
                            else dp.at(i+1) += dp.at(i);
                        }
                    }
                }
            }
        }
        bool ng = false;
        for(int i=4; i>=0; i--){
            if(i == 0){ng = true; break;}
            if(t.at(i) == 'Z') t.at(i) = 'A';
            else{t.at(i)++; break;}
        }
        if(ng) break;
        t.at(0) = t.at(2);
    }
    cout << answer << endl;
}