AtCoder Beginner Contest 089
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Problem Statement
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There are $N$ people. The name of the $i$-th person is $S_i$.
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We would like to choose three people so that the following conditions are met:
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- The name of every chosen person begins with
M,A,R,CorH. - There are no multiple people whose names begin with the same letter.
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How many such ways are there to choose three people, disregarding order?
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Note that the answer may not fit into a $32$-bit integer type.
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Constraints
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$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)$
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Input
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Input is given from Standard Input in the following format:
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N
S_1
:
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Output
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If there are $x$ ways to choose three people so that the given conditions are met, print $x$.
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样例
Input #1
5
MASHIKE
RUMOI
OBIRA
HABORO
HOROKANAI
Output #1
2
We can choose three people with the following names:
- `MASHIKE`, `RUMOI`, `HABORO`
- `MASHIKE`, `RUMOI`, `HOROKANAI`
Thus, we have two ways.
Input #2
4
ZZ
ZZZ
Z
ZZZZZZZZZZ
Output #2
0
Note that there may be no ways to choose three people so that the given conditions are met.
Input #3
5
CHOKUDAI
RNG
MAKOTO
AOKI
RINGO
Output #3
7
题目信息
题面与样例版权归 AtCoder 及出题人所有；中文翻译由 AI 生成（CI 管线），如有出入请以原文为准。