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 Java (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.*;
import java.math.*;
import java.util.*;
public class Main{ 
 
	public static void main(String[] args) { 
		FastScanner I = new FastScanner(); //Input
		OutPut O = new OutPut(); //Output
		int N = I.nextInt();
		long ans = 0;
		long[] cnts = new long[5]; //M start, A start, R start, C, start, H start
		for (int i = 0; i < N; i++) {
			String S = I.next();
			if (S.charAt(0)=='M') cnts[0]++;
			else if (S.charAt(0)=='A') cnts[1]++;
			else if (S.charAt(0)=='R') cnts[2]++;
			else if (S.charAt(0)=='C') cnts[3]++;
			else if (S.charAt(0)=='H') cnts[4]++;
		}
		for (int i = 0; i < 5; i++) {
			for (int j = i+1; j < 5; j++) {
				for (int k = j+1; k < 5; k++) {
					ans+=cnts[i]*cnts[j]*cnts[k];
				}
			}
		}
		O.pln(ans);
	}	
	public static void build(int[][] segtree,String S,int start, int end, int node) {
		if (start==end) {
			int[] cnts = new int[26];
			cnts[(int)(S.charAt(start))-97]++;
			for (int i = 0; i < 26; i++) segtree[node][i]=cnts[i];
		}else {
			int mid = (start+end)/2;
			build(segtree,S,start,mid,2*node); //Left child recursion
			build(segtree,S,mid+1,end,2*node+1);
			for (int i = 0; i < 26; i++) {
				segtree[node][i] = segtree[2*node][i]+segtree[2*node+1][i];
			}
		}
	}
	public static void UPD(int[][] segtree,String S,int start, int end, int in, 
	char val, int node) {
		if (start==end) {
			int prev = 0;
			for (int i = 0; i < 26; i++) { //Use the segment tree for referring to previous
				//data
				if (segtree[node][i]>0) {
					prev=i;
					break;
				}
			}
			segtree[node][prev]--;
			segtree[node][(int)(val)-97]++;
		}else {
			int mid = (start+end)/2;
			if (in>=start&&in<=mid) { //left child
				UPD(segtree,S,start,mid,in,val,2*node);
			}else if (in>mid&&in<=end){ //Right child
				UPD(segtree,S,mid+1,end,in,val,2*node+1);
			}
			for (int i = 0; i < 26; i++) {
				segtree[node][i]=segtree[node*2][i]+segtree[node*2+1][i];
			}
		}
	}
	public static int[] getAns(int[][] segtree,String S,int start,int end,
	int L, int R, int node) {
		int[] ret = new int[26];
		if (L>end||R<start) { //Out of range case
			return ret; //Return empty array (no affect on answer)
		}
		if (L<=start&&R>=end) { //Surrounded node case
			return segtree[node]; //Returning data stored in the surrounded node
		}
		int mid = (start+end)/2;
		int[] left = getAns(segtree,S,start,mid,L,R,2*node);
		int[] right = getAns(segtree,S,mid+1,end,L,R,2*node+1);
		for (int i = 0; i < 26; i++) ret[i] = left[i]+right[i]; //Parent data = children data sum
		return ret;
	}
	public static long ceil(long num, long den) {long ans = num/den; if (num%den!=0) 
	ans++; return ans;}
	public static long GCD(long a, long b) {
		if (a==0||b==0) return Math.max(a,b);
		return GCD(Math.min(a, b),Math.max(a, b)%Math.min(a, b));
	}
	public static long FastExp(long base, long exp, long mod) {
		long ans=1;
		while (exp>0) {
			if (exp%2==1) ans*=base;
			exp/=2;
			base*=base;
			base%=mod;
			ans%=mod;
		}
		return ans;
	}
	public static long ModInv(long num,long mod) {return FastExp(num,mod-2,mod);}
	public static int pop(long x) { //Returns number of bits within a number
		int cnt = 0;
		while (x>0) {
			if (x%2==1) cnt++;
			x/=2;
		}
		return cnt;
	}
	static class FastScanner {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st=new StringTokenizer("");
		String next() {
			while (!st.hasMoreTokens())
				try {
					st=new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			return st.nextToken();
		}
		int nextInt() {return Integer.parseInt(next());}
		long nextLong() {return Long.parseLong(next());};
	}
	static class OutPut{
		PrintWriter w = new PrintWriter(System.out);
		void pln(int x) {w.println(x);w.flush();}
		void pln(long x) {w.println(x);w.flush();}
		void pln(String x) {w.println(x);w.flush();}
		void pln(char x) {w.println(x);w.flush();}
		void pln(StringBuilder x) {w.println(x);w.flush();}
		void pln(BigInteger x) {w.println(x);w.flush();}
		void p(int x) {w.print(x);w.flush();}
		void p(long x) {w.print(x);w.flush();}
		void p(String x) {w.print(x);w.flush();}
		void p(char x) {w.print(x);w.flush();}
		void p(StringBuilder x) {w.print(x);w.flush();}
		void p(BigInteger x) {w.print(x);w.flush();}
	}
}