Problem:
Score : 200 points

Problem Statement

You are given a string S. Each character of S is uppercase or lowercase English letter.
Determine if S satisfies all of the following conditions:

The initial character of S is an uppercase A.

There is exactly one occurrence of C between the third character from the beginning and the second to last character (inclusive).

All letters except the A and C mentioned above are lowercase.

Constraints

4 ≤ |S| ≤ 10 (|S| is the length of the string S.)

Each character of S is uppercase or lowercase English letter.

Input

Input is given from Standard Input in the following format:

S

Output

If S satisfies all of the conditions in the problem statement, print AC; otherwise, print WA.

Sample Input 1

AtCoder

Sample Output 1

AC

The first letter is A, the third letter is C and the remaining letters are all lowercase, so all the conditions are satisfied.

Sample Input 2

ACoder

Sample Output 2

WA

The second letter should not be C.

Sample Input 3

AcycliC

Sample Output 3

WA

The last letter should not be C, either.

Sample Input 4

AtCoCo

Sample Output 4

WA

There should not be two or more occurrences of C.

Sample Input 5

Atcoder

Sample Output 5

WA

The number of C should not be zero, either.

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

class String
  def is_lower?
    self == self.downcase
  end
end

# 初期値
s = gets.chomp.chars
res = [false, false, false]

# 1つめの条件
if s[0] === 'A'
  res[0] = true
end

# 2つめの条件
pos = nil

tmp_s1 = s.slice(2..-2)
c_count = tmp_s1.select{|i| i === 'C'}.count
if c_count === 1
  pos = s.index('C')
  res[1] = true
end

# 3つめの条件
tmp_s = s
if !pos.nil?
  [pos, 0].each do |i|
    tmp_s.delete_at(i)
  end
else
  tmp_s.delete_at(0)
end

res[2] = true if tmp_s.count === tmp_s.select{|i|i.is_lower?}.count

puts res == [true, true, true] ? 'AC' : 'WA'