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
{
    static Scanner sc = new Scanner();
    static void Main(string[] args)
    {
        var N = sc.ReadInt();
        var S = sc.ReadStrArray(N);

        var m = 0;
        var a = 0;
        var r = 0;
        var c = 0;
        var h = 0;

        for (int i = 0; i < N; i++)
        {
            if (S[i][0] == 'M') m++;
            else if (S[i][0] == 'A') a++;
            else if (S[i][0] == 'R') r++;
            else if (S[i][0] == 'C') c++;
            else if (S[i][0] == 'H') h++;
        }

        var counts = new int[5] { m, a, r, c, h };
        if (counts.Count(x => x == 0) >= 3)
        {
            Console.WriteLine(0);
        }
        else
        {
            var ans = 0L;
            var seq = counts.Where(x => x != 0).ToArray();
            for (int i = 0; i < seq.Count(); i++)
            {
                for (int j = i + 1; j < seq.Count(); j++)
                {
                    for (int k = j + 1; k < seq.Count(); k++)
                    {
                        ans += seq[i] * seq[j] * seq[k];
                    }
                }
            }
            Console.WriteLine(ans);
        }
    }
}

class Modulo
{
    public readonly int MOD;
    private readonly List<int> Facs = new List<int>() { 1 };

    public Modulo(int mod = 1000000007) { this.MOD = mod; }
    public int Mul(int a, int b) { return (int)(Math.BigMul(a, b) % MOD); }
    public int Div(int a, int b) { return Mul(a, Pow(b, MOD - 2)); }
    public int Pow(int a, int n)
    {
        switch (n)
        {
            case 0:
                return 1;
            case 1:
                return a;
            default:
                int p1 = Pow(a, n / 2);
                int p2 = Mul(p1, p1);
                return ((n % 2) == 0) ? p2 : Mul(p2, a);
        }
    }
    public int Fac(int n)
    {
        for (int i = this.Facs.Count; i <= n; i++)
        {
            this.Facs.Add(Mul(i, Facs[i - 1]));
        }
        return this.Facs[n];
    }
    public int nPr(int n, int r) => Div(Fac(n), Fac(n - r));
    public int nCr(int n, int r)
    {
        if (n < r) return 0;
        if (n == r) return 1;
        int res = Fac(n);
        res = Div(res, Fac(r));
        res = Div(res, Fac(n - r));
        return res;
    }
}

class Debug
{
    public static void Dump<T>(T[,] array)
    {
        Console.WriteLine();
        var h = array.GetLength(0);
        var w = array.GetLength(1);

        for (int r = 0; r < h; r++)
        {
            for (int c = 0; c < w; c++)
            {
                Console.Write(array[r, c]);
                Console.Write(" ");
            }
            Console.WriteLine();
        }
        Console.WriteLine();
    }
    public static void Dump<T>(T[] array)
    {
        Console.WriteLine();
        Console.WriteLine(string.Join(" ", array));
        Console.WriteLine();
    }
}

class Scanner
{
    string[] S = new string[0];
    int Index = 0;
    char[] Separators = new char[] { ' ' };

    public string Next()
    {
        if (this.Index < this.S.Length) return this.S[this.Index++];
        var line = "";
        while (line == "") line = Console.ReadLine();
        this.S = line.Split(this.Separators, StringSplitOptions.RemoveEmptyEntries);
        if (this.S.Length == 0) return this.Next();
        this.Index = 0;
        return this.S[this.Index++];
    }

    public string ReadStr()
    {
        return this.Next();
    }

    public char ReadChar()
    {
        return this.Next()[0];
    }

    public int ReadInt()
    {
        return int.Parse(this.Next());
    }

    public uint ReadUInt()
    {
        return uint.Parse(this.Next());
    }

    public long ReadLong()
    {
        return long.Parse(this.Next());
    }

    public int[] ReadIntArray(int n)
    {
        var array = new int[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadInt();
        }
        return array;
    }

    public long[] ReadLongArray(int n)
    {
        var array = new long[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadLong();
        }
        return array;
    }

    public char[] ReadCharArray(int n)
    {
        var array = new char[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadChar();
        }
        return array;
    }

    public string[] ReadStrArray(int n)
    {
        var array = new string[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadStr();
        }
        return array;
    }
}

class HashMap<K, V> : Dictionary<K, V> where V : new()
{
    private V DefaltValue = new V();
    public HashMap() { }
    public HashMap(V defaultValue)
    {
        this.DefaltValue = new V();
    }
    new public V this[K i]
    {
        get
        {
            V v;
            return TryGetValue(i, out v) ? v : base[i] = this.DefaltValue;
        }
        set { base[i] = value; }
    }
}