Problem:
Score : 300 points

Problem Statement

There are N people. The name of the i-th person is S_i.

We would like to choose three people so that the following conditions are met:

The name of every chosen person begins with M, A, R, C or H.

There are no multiple people whose names begin with the same letter.

How many such ways are there to choose three people, disregarding order?

Note that the answer may not fit into a 32-bit integer type.

Constraints

1 \leq N \leq 10^5

S_i consists of uppercase English letters.

1 \leq |S_i| \leq 10

S_i \neq S_j (i \neq j)

Input

Input is given from Standard Input in the following format:

N
S_1
:
S_N

Output

If there are x ways to choose three people so that the given conditions are met, print x.

Sample Input 1

5
MASHIKE
RUMOI
OBIRA
HABORO
HOROKANAI

Sample Output 1

2

We can choose three people with the following names:

MASHIKE, RUMOI, HABORO

MASHIKE, RUMOI, HOROKANAI

Thus, we have two ways.

Sample Input 2

4
ZZ
ZZZ
Z
ZZZZZZZZZZ

Sample Output 2

0

Note that there may be no ways to choose three people so that the given conditions are met.

Sample Input 3

5
CHOKUDAI
RNG
MAKOTO
AOKI
RINGO

Sample Output 3

7

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
class Program
{
    long mod = 1000000009;
    static void Main(string[] args)
    {
        long n = long.Parse(Read.Str());
        List<char> cap = new List<char> { };
        HashSet<char> kab =new HashSet<char> { };
        for(long i = 0; i < n; i++)
        {
            char Jksd = Console.ReadLine()[0];
            cap.Add(Jksd);
        }
        for (int i = 0; i < cap.Count(); i++)
        {
            if (cap[i] == 'M' || cap[i] == 'A' || cap[i] == 'R' || cap[i] == 'C' || cap[i] == 'H')
            {
            }
            else
            {
                cap.Remove(cap[i]);
            }
        }
        long[] a = new long[5];
        for (long i = 0; i < cap.Count(); i++)
        {
            if (cap[(int)i] == 'M') { a[0]++; }
            else if (cap[(int)i] == 'A') { a[1]++; }
            else if (cap[(int)i] == 'R') { a[2]++; }
            else if (cap[(int)i] == 'C') { a[3]++; }
            else { a[4]++; }
        }
        Array.Sort(a);
        if (a[2] == 0) { Console.WriteLine(0); }
        else if (a[1] == 0) { Console.WriteLine(a[2] * a[3] * a[4]); }
        else if (a[0] == 0)
        {
            long ans = 0;
            for (int i = 1; i < 5; i++)
            {
                for (int j = i + 1; j < 5; j++)
                {
                    for (int k = j + 1; k < 5; k++)
                    {
                        ans += a[i] * a[j] * a[k];
                    }
                }
            }
            Console.WriteLine(ans);
        }
        else
        {
            long ans = 0;
            for (int i = 0; i < 5; i++)
            {
                for (int j = i + 1; j < 5; j++)
                {
                    for (int k = i + 1; k < 5; k++)
                    {
                        ans += a[i] * a[j] * a[k];
                    }
                }
            }
            Console.WriteLine(ans);
        }
        Console.ReadLine();
    } public static long gcd(long a, long b)
    {
        while (true)
        {
            if (a == 0) { return b; }
            if (b == 0) { return a; }
            if (a > b) { a -= b; }
            else { b -= a; }
        }
    }
    public static long lcm(long a, long b) { return a / gcd(a, b) * b; }
    public static bool IsPrime(int num)
    {
        if (num < 2) return false;
        else if (num == 2) return true;
        else if (num % 2 == 0) return false; // 偶数はあらかじめ除く

        double sqrtNum = Math.Sqrt(num);
        for (int i = 3; i <= sqrtNum; i += 2)
        {
            if (num % i == 0)
            {
                // 素数ではない
                return false;
            }
        }

        // 素数である
        return true;
    }
}
public static class Read
{
    public static void outl(string n = "") { Console.WriteLine(n); return; }
    public static long Long() { return long.Parse(Console.ReadLine()); }
    public static long[] longs() { return Console.ReadLine().Split().Select(long.Parse).ToArray(); }
    public static int Int() { return int.Parse(Console.ReadLine()); }
    public static int[] ints() { return Console.ReadLine().Split().Select(int.Parse).ToArray(); }
    public static string Str() { return Console.ReadLine(); }
    public static string[] Strs() { return Console.ReadLine().Split(); }
}