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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
        public static void main(String[] args) {
                InputStream inputStream = System.in;
                OutputStream outputStream = System.out;
                InputReader in = new InputReader(inputStream);
                PrintWriter out = new PrintWriter(outputStream);
                TaskC solver = new TaskC();
                solver.solve(1, in, out);
                out.close();
        }

        static class TaskC {
                int[][] perm = new int[10][3];
                int ind = 0;

                public void solve(int testNumber, InputReader in, PrintWriter out) {
                        //generatePermutation(new int[]{0,1,2},3,3);
                        getCombination(new int[]{0, 1, 2, 3, 4}, 5, 3);
                        //for (int i = 0; i < 10; i++) out.println(Arrays.toString(perm[i]));
                        int n = in.i();
                        long[] d = new long[5];
                        for (int i = 0; i < n; i++) {
                                String s = in.s();
                                if (s.charAt(0) == 'M') d[0]++;
                                if (s.charAt(0) == 'A') d[1]++;
                                if (s.charAt(0) == 'R') d[2]++;
                                if (s.charAt(0) == 'C') d[3]++;
                                if (s.charAt(0) == 'H') d[4]++;
                        }

                        long ans = 0;
                        for (int i = 0; i < 10; i++) {
                                ans += d[perm[i][0]] * d[perm[i][1]] * d[perm[i][2]];
                        }
                        out.println(ans);
                }

                void getCombination(int[] a, int n, int r) {
                        int[] data = new int[n];
                        combinationUtil(a, n, r, 0, data, 0);
                }

                private void combinationUtil(int[] a, int n, int r, int index, int[] data, int i) {
                        if (index == r) {
                                perm[ind++] = Arrays.copyOf(data, r);
                                return;
                        }
                        if (i >= n) return;
                        data[index] = a[i];
                        combinationUtil(a, n, r, index + 1, data, i + 1);
                        combinationUtil(a, n, r, index, data, i + 1);
                }

        }

        static class InputReader {
                InputStream is;
                private byte[] inbuf = new byte[1024];
                public int lenbuf = 0;
                public int ptrbuf = 0;

                public InputReader(InputStream is) {
                        this.is = is;
                }

                private int readByte() {
                        if (lenbuf == -1) throw new InputMismatchException();
                        if (ptrbuf >= lenbuf) {
                                ptrbuf = 0;
                                try {
                                        lenbuf = is.read(inbuf);
                                } catch (IOException e) {
                                        throw new InputMismatchException();
                                }
                                if (lenbuf <= 0) return -1;
                        }
                        return inbuf[ptrbuf++];
                }

                private boolean isSpaceChar(int c) {
                        return !(c >= 33 && c <= 126);
                }

                private int skip() {
                        int b;
                        while ((b = readByte()) != -1 && isSpaceChar(b)) ;
                        return b;
                }

                public String s() {
                        int b = skip();
                        StringBuilder sb = new StringBuilder();
                        while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
                                sb.appendCodePoint(b);
                                b = readByte();
                        }
                        return sb.toString();
                }

                public int i() {
                        int num = 0, b;
                        boolean minus = false;
                        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')) ;
                        if (b == '-') {
                                minus = true;
                                b = readByte();
                        }

                        while (true) {
                                if (b >= '0' && b <= '9') {
                                        num = num * 10 + (b - '0');
                                } else {
                                        return minus ? -num : num;
                                }
                                b = readByte();
                        }
                }

        }
}