using System.Linq;
using System.Collections.Generic;
using System;

public static class combi
{
    public static IEnumerable<IEnumerable<T>> Comb<T>(this IEnumerable<T> items, int r)
    {
        if (r == 0)
        {
            yield return Enumerable.Empty<T>();
        }
        else
        {
            var i = 1;
            foreach (var x in items)
            {
                var xs = items.Skip(i);
                foreach (var c in Comb(xs, r - 1))
                    yield return c.Before(x);
                i++;
            }
        }
    }
    public static IEnumerable<T> Before<T>(this IEnumerable<T> items, T first)
    {
        yield return first;
        foreach (var i in items)
            yield return i;
    }
}


public class Hello
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        var s = Console.ReadLine().Trim();
        getAns(n, s);
    }
    static bool check(int[] a, string s)
    {
        if (s[a[0]] != s[a[2]]) return false;
        if (s[a[0]] == s[a[1]]) return false;
        if (s[a[0]] == s[a[3]]) return false;
        if (s[a[0]] == s[a[4]]) return false;
        var hs = new HashSet<char>();
        hs.Add(s[a[1]]);
        hs.Add(s[a[3]]);
        hs.Add(s[a[4]]);
        return hs.Count == 3;
    }
    static void getAns(int n, string s)
    {
        var a = Enumerable.Range(0, n).Comb(5);
        var ans = 0;
        foreach (var x in a)
        {
            var y = x.ToArray();
            if (check(y, s)) ans++;
        }
        Console.WriteLine(ans);
    }
}