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)

def bb
    s = gets.chomp

    # 先頭A
    unless s[0] == 'A'
        puts 'WA'
        exit
    end

    # Cは3文字目、末尾から2文字目の間に１つ
    cn = []
    idx = 0
    s.each_char do |c|
        cn.push(idx) if c == 'C'
        idx += 1
    end
    unless cn.length == 1
        puts 'WA'
        exit
    end
    unless cn[0] >= 2 and cn[0] <= s.length-2
        puts 'WA'
        exit
    end

    swoac = s.delete('A').delete('C')
    if swoac == swoac.downcase
        puts 'AC'
    else
        puts 'WA'
    end
end

bb