题目描述
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.
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.
Constraints
- $1 \leq N \leq 10^5$
- S_i consists of uppercase English letters.
- $1 \leq |S_i| \leq 10$
- $S_i \neq S_j (i \neq j)$
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
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分