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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Text.RegularExpressions;

namespace ConsoleApp1
{
    class Program
    {
  
        static void Main(string[] args)
        {
            string S = Console.ReadLine();
            Boolean ok = false;
            int cnt = 0;
            int len = S.Length;
            if (S.Substring(0, 1) == "A"
             && S.Substring(1, 1) == S.Substring(1, 1).ToLower()
             && S.Substring(len - 1, 1) == S.Substring(len - 1, 1).ToLower())
            {
                for (int i = 2; i < len - 1; i++)
                {
                    if (S.Substring(i, 1) != S.Substring(i, 1).ToLower())
                    {
                        if (S.Substring(i, 1) != "C")
                        {
                            ok = false;
                            break;
                        }
                        else
                        {
                            cnt++;
                            ok = true;
                        }
                    }
                    else
                    {
                        ok = true;
                    }
                }
                if (cnt != 1)
                    ok = false;
            }
            if(ok)
            {
                Console.WriteLine("AC");
            }
            else
            {
                Console.WriteLine("WA");
            }
        }
    }
}