Problem:
Score : 100 points

Problem Statement

On the Planet AtCoder, there are four types of bases: A, C, G and T. A bonds with T, and C bonds with G.

You are given a letter b as input, which is A, C, G or T. Write a program that prints the letter representing the base that bonds with the base b.

Constraints

b is one of the letters A, C, G and T.

Input

Input is given from Standard Input in the following format:

b

Output

Print the letter representing the base that bonds with the base b.

Sample Input 1

A

Sample Output 1

T

Sample Input 2

G

Sample Output 2

C

Solution in PHP7 (7.0.15) (judge verdict: Accepted)

#!/usr/bin/env php
<?php

$inputs = [];
while (($item = fgets(STDIN)) !== false) {
    $inputs[] = $item;
}

$map = [
    'A' => 'T',
    'T' => 'A',
    'C' => 'G',
    'G' => 'C',
];
$x = trim(array_shift($inputs));
echo $map[$x].PHP_EOL;