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 C# (Mono-mcs 6.8.0.105) (judge verdict: Accepted)

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

class Program
{
	static void Main()
	{
		var array1 = new[] { 'A', 'C', 'G', 'T' };
		var array2 = new[] { 'T', 'G', 'C', 'A' };

		var b = Console.ReadLine().First();
		Console.WriteLine(array2[Array.IndexOf(array1, b)]);

		//デバッグ実行での確認用。そのまま提出しても問題なし
		Console.ReadKey();
	}
}