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 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections;

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine(DoubleHelix());
    }

    private static string DoubleHelix()
    {
        Hashtable ht = new Hashtable();
        ht.Add("A", "T");
        ht.Add("C", "G");
        ht.Add("G", "C");
        ht.Add("T", "A");

        string b = string.Empty;

        readData(ref b);

        return (string)ht[b];
    }

    /// <summary>
    /// データを読み込む
    /// </summary>
    private static void readData(ref string b)
    {
        b = Console.ReadLine();
    }
}