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: Accepted)

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

namespace Contest
{
  class Program
  {
    static void Main(string[] args)
    {
      ABC089.C();
    }
    class ABC088
    {
      public static void A()
      {
        var N = Read.Int();
        var A = Read.Int();
        Console.WriteLine(N % 500 <= A ? "Yes" : "No");
      }
      public static void B()
      {
        var N = Read.Int();
        var A = Read.IntN().OrderBy(x => -x).ToArray();
        Console.WriteLine(A.Select((x, i) => i % 2 == 0 ? x : -x).Sum());
      }
      public static void C()
      {
        var C = Read.LongMatrix(3, 3);
        bool ok = true;
        for(int i = 0; i < 2; ++i)
        {
          if (C[i, 0] - C[i + 1, 0] != C[i, 1] - C[i + 1, 1]) { ok = false; }
          if (C[i, 0] - C[i + 1, 0] != C[i, 2] - C[i + 1, 2]) { ok = false; }
          if (C[i, 1] - C[i + 1, 1] != C[i, 2] - C[i + 1, 2]) { ok = false; }
          if (C[0, i] - C[0, i + 1] != C[1, i] - C[1, i + 1]) { ok = false; }
          if (C[0, i] - C[0, i + 1] != C[2, i] - C[2, i + 1]) { ok = false; }
          if (C[1, i] - C[1, i + 1] != C[2, i] - C[2, i + 1]) { ok = false; }
        }
        Console.WriteLine(ok ? "Yes" : "No");
      }
      public static void D()
      {
        var H = Read.Int();
        var W = Read.Int();
        var S = Enumerable.Range(0, H).Select(i => Read.Str()).ToArray();
        var board = new bool[H + 2, W + 2];
        int white = 0;
        for(int i = 0; i < H; ++i)
        {
          for(int j = 0; j < W; ++j)
          {
            board[i + 1, j + 1] = S[i][j] == '.';
            if(S[i][j] == '.') { white++; }
          }
        }
        var dx = new int[] { 1, -1, 0, 0 };
        var dy = new int[] { 0, 0, 1, -1 };
        var dist = Util.Gen(H + 2, W + 2, -1);
        dist[1, 1] = 0;
        var queue = new Queue<Tuple<int, int>>();
        queue.Enqueue(new Tuple<int, int>(1, 1));
        while (queue.Count > 0)
        {
          var t = queue.Dequeue();
          for(int i = 0; i < 4; ++i)
          {
            var x = t.Item1 + dx[i];
            var y = t.Item2 + dy[i];
            if (dist[x, y] < 0 && board[x, y])
            {
              dist[x, y] = dist[t.Item1, t.Item2] + 1;
              queue.Enqueue(new Tuple<int, int>(x, y));
            }
          }
        }
        if (dist[H, W] < 0) { Console.WriteLine(-1);return; }
        Console.WriteLine(white - 1 - dist[H, W]);
      }
    }
    class ABC089
    {
      public static void A()
      {
        var N = Read.Int();
        Console.WriteLine(N / 3);
      }
      public static void B()
      {
        var N = Read.Int();
        var S = Read.StrN();
        Console.WriteLine(S.Contains("Y") ? "Four" : "Three");
      }
      public static void C()
      {
        var N = Read.Int();
        var S = Enumerable.Range(0, N).Select(i => Read.Str()).ToArray();
        var count = new long[5];
        foreach(var s in S)
        {
          switch (s[0])
          {
            case 'M': count[0]++; break;
            case 'A': count[1]++; break;
            case 'R': count[2]++; break;
            case 'C': count[3]++; break;
            case 'H': count[4]++; break;
          }
        }
        long sum = 0;
        for(int i = 0; i < 5; ++i)
        {
          for(int j = i + 1; j < 5; ++j)
          {
            for(int k = j + 1; k < 5; ++k)
            {
              sum += count[i] * count[j] * count[k];
            }
          }
        }
        Console.WriteLine(sum);
      }
      public static void D()
      {
        var H = Read.Int();
        var W = Read.Int();
        var D = Read.Int();
        var A = Read.LongMatrix(H, W);
        var place = new Tuple<int, int>[H * W + 1];
        for(int i = 0; i < H; ++i)
        {
          for(int j = 0; j < W; ++j)
          {
            place[(int)A[i, j]] = new Tuple<int, int>(i, j);
          }
        }
        var Q = Read.Int();
        var LR = Read.TupleInt(Q);
        var distance = new List<int>[D];
        for(int i = 0; i < D; ++i)
        {
          var list = new List<int>();
          distance[i] = list;
          list.Add(0);
          for (int j = 1; ; ++j)
          {
            var prev = i + D * (j - 1);
            var next = i + D * j;
            if (next > H * W) { break; }
            if (prev == 0) { list.Add(0); continue; }
            var d = Math.Abs(place[prev].Item1 - place[next].Item1) + Math.Abs(place[prev].Item2 - place[next].Item2);
            list.Add(list.Last() + d);
          }
        }
        var ans = new List<int>();
        foreach(var lr in LR)
        {
          var c = lr.Item1 % D;
          var s = lr.Item1 / D;
          var t = lr.Item2 / D;
          ans.Add(distance[c][t] - distance[c][s]);
        }
        Console.WriteLine(String.Join(Environment.NewLine, ans));
      }
    }


    class Util
    {
      public static T[,] Gen<T>(int r, int c, T v)
      {
        var matrix = new T[r, c];
        for (int i = 0; i < r; ++i)
        {
          for (int j = 0; j < c; ++j)
          {
            matrix[i, j] = v;
          }
        }
        return matrix;
      }
      public static long[] ASum(long[] array)
      {
        var res = new long[array.Length + 1];
        for (int i = 0; i < array.Length; ++i)
        {
          res[i + 1] = res[i] + array[i];
        }
        return res;
      }
      public static long[,] ASum(long[,] matrix)
      {
        var N = matrix.GetLength(0);
        var M = matrix.GetLength(1);
        var res = new long[N + 1, M + 1];
        for(int i = 0; i < N; ++i)
        {
          for(int j = 0; j < M; ++j)
          {
            res[i + 1, j + 1] = res[i, j + 1] + res[i + 1, j] - res[i, j] + matrix[i, j];
          }
        }
        return res;
      }
      public static Dictionary<T, long> Frequency<T>(T[] array)
      {
        var dict = new Dictionary<T, long>();
        foreach (var a in array)
        {
          if (!dict.ContainsKey(a)) { dict.Add(a, 0); }
          dict[a]++;
        }
        return dict;
      }
      public static bool IsPrime(long x)
      {
        var fact = Factorize(x);
        return fact.Count == 1 && fact.Values.ElementAt(0) == 1;
      }
      public static Dictionary<long, int> Factorize(long x)
      {
        var dict = new Dictionary<long, int>();
        long minp = 2;
        while (x > 1)
        {
          bool ok = false;
          for (long p = minp; p * p <= x; ++p)
          {
            if (x % p == 0)
            {
              if (!dict.ContainsKey(p))
              {
                dict.Add(p, 0);
              }
              dict[p]++;
              minp = p;
              x /= p;
              ok = true;
              break;
            }
          }
          if (!ok)
          {
            if (!dict.ContainsKey(x)) { dict.Add(x, 0); }
            dict[x]++;
            break;
          }
        }
        return dict;
      }
    }

    static class Read
{
static Queue<string> queue = new Queue<string>();
static void Enqueue() { var ss = Console.ReadLine().Split(' '); foreach (var s in ss) { queue.Enqueue(s); } }
public static int Int() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt32(queue.Dequeue()); }
public static long Long() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt64(queue.Dequeue()); }
public static string Str() { if (queue.Count == 0) { Enqueue(); } return queue.Dequeue(); }
public static int[] IntN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt32(s)).ToArray(); }
public static long[] LongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray(); }
public static ulong[] ULongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToUInt64(s)).ToArray(); }
public static string[] StrN() { return Console.ReadLine().Split(' '); }
public static Tuple<int, int>[] TupleInt(int n) { List<Tuple<int, int>> list = new List<Tuple<int, int>>(); for (int i = 0; i < n; ++i) { var ab = Read.IntN(); list.Add(new Tuple<int, int>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<long, long>[] TupleLong(int n) { List<Tuple<long, long>> list = new List<Tuple<long, long>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<long, long>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<string, string>[] TupleStr(int n) { List<Tuple<string, string>> list = new List<Tuple<string, string>>(); for (int i = 0; i < n; ++i) { var ab = Read.StrN(); list.Add(new Tuple<string, string>(ab[0], ab[1])); } return list.ToArray(); }
public static Tuple<double, double>[] TupleDouble(int n) { List<Tuple<double, double>> list = new List<Tuple<double, double>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<double, double>(ab[0], ab[1])); } return list.ToArray(); }
public static long[,] LongMatrix(int r, int c) { var mat = new long[r, c]; for (int i = 0; i < r; ++i) { var x = Read.LongN(); for (int j = 0; j < c; ++j) { mat[i, j] = x[j]; } } return mat; }
public static Dictionary<int, HashSet<int>> AdjacencyList(int N, int M, bool isDirectional = false)
{
Dictionary<int, HashSet<int>> dict = new Dictionary<int, HashSet<int>>();
for (int i = 0; i <= N; ++i) { dict.Add(i, new HashSet<int>()); }
        for (int i = 0; i < M; ++i) { var ab = Read.IntN(); if (!dict[ab[0]].Contains(ab[1])) { dict[ab[0]].Add(ab[1]); } if (!isDirectional && !dict[ab[1]].Contains(ab[0])) { dict[ab[1]].Add(ab[0]); } }
        return dict;
}
public static Dictionary<int, Dictionary<int, long>> AdjacencyListWithWeight(int N, int M)
{
Dictionary<int, Dictionary<int, long>> dict = new Dictionary<int, Dictionary<int, long>>(); for (int i = 0; i <= N; ++i) { dict.Add(i, new Dictionary<int, long>()); }
for (int i = 0; i < M; ++i) { var ab = Read.IntN(); dict[ab[0]].Add(ab[1], ab[2]); dict[ab[1]].Add(ab[0], ab[2]); }
return dict;
}
}
    }
}