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 Perl (v5.18.2) (judge verdict: Accepted)

#!/usr/bin/perl

my $s = <STDIN>;
$s =~ s/[\x00-\x20]+$//io;

unless( $s =~ /^A/o ){
  print "WA\n" ;
  exit(0);
}
substr($s,0,1) = 'a';

my $cc = 0;
for(my $i=2;$i<length($s)-1;$i++){
  if( substr($s,$i,1) eq 'C'){
    $cc++;
    substr($s,$i,1) = 'c';
  }
}

if( $cc != 1 ){
  print "WA\n" ;
  exit(0);
}

unless( $s =~ /^[a-z]+$/o ){
  print "WA\n" ;
  exit(0);
}

print "AC\n";

exit(0);