题目描述
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-----
5
MASHIKE
RUMOI
OBIRA
HABORO
HOROKANAI
-----Sample Output-----
2
We can choose three people with the following names:
- MASHIKE, RUMOI, HABORO
- MASHIKE, RUMOI, HOROKANAI
Thus, we have two ways.
输入格式
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输出格式
见题面