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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace AtCoder_Project_CSharp
{
    class Program
    {

        static void Main(string[] args)
        {
            var s = (Console.ReadLine());

            var alphabet = new HashSet<int>(Enumerable.Range('a', 26));

            if (s[0] == 'A')
            {
                for (int i = 2; i < s.Length - 2; i++)
                {
                    if(s[i]=='C')
                    {
                        bool flag = false;
                        for (int j = 1; j < s.Length; j++)
                        {
                            if (i == j) continue;
                            if(!alphabet.Contains(s[j]))
                            {
                                flag = true;
                                break;   
                            }
                        }
                        if(!flag)
                        {
                            Console.WriteLine("AC");
                            return;
                        }
                    }
                }
            }
            Console.WriteLine("WA");
            

        }
    }
}