Problem:
Score : 400 points

Problem Statement

Snuke has N strings. The i-th string is s_i.

Let us concatenate these strings into one string after arranging them in some order.
Find the maximum possible number of occurrences of AB in the resulting string.

Constraints

1 \leq N \leq 10^{4}

2 \leq |s_i| \leq 10

s_i consists of uppercase English letters.

Input

Input is given from Standard Input in the following format:

N
s_1
\vdots
s_N

Output

Print the answer.

Sample Input 1

3
ABCA
XBAZ
BAD

Sample Output 1

2

For example, if we concatenate ABCA, BAD and XBAZ in this order, the resulting string ABCABADXBAZ has two occurrences of AB.

Sample Input 2

9
BEWPVCRWH
ZZNQYIJX
BAVREA
PA
HJMYITEOX
BCJHMRMNK
BP
QVFABZ
PRGKSPUNA

Sample Output 2

4

Sample Input 3

7
RABYBBE
JOZ
BMHQUVA
BPA
ISU
MCMABAOBHZ
SZMEHMA

Sample Output 3

4

Solution in Ruby (2.3.3) (judge verdict: Accepted)

# https://atcoder.jp/contests/diverta2019/tasks/diverta2019_c

n = gets.to_i
res = 0

def is_left(word)
  word[0] != 'B' && word[-1] == 'A'
end

def is_mid(word)
  word[0] == 'B' && word[-1] == 'A'
end

def is_right(word)
  word[0] == 'B' && word[-1] != 'A'
end


lefts = []
rights = []
mids = []
words = []

n.times do
  word = gets.chomp
  res += word.scan('AB').size
  if is_left(word)
    lefts << word
  elsif is_mid(word)
    mids << word
  elsif is_right(word)
    rights << word
  end
  words << word
end

minsize = [lefts.size, rights.size].min

if mids.size == 0
  res += minsize
elsif lefts.size + rights.size == 0
  res += mids.size - 1
else
  res += [lefts.size, rights.size].min + mids.size
end

puts res