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.IO;

namespace ABC122A
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length > 0)
            {
                Console.SetIn(new StreamReader(args[0]));
            }

            new Program().Solve();
        }

        void Solve()
        {
            var b = Console.ReadLine();
            var ans = "";

            if (b == "A")
            {
                ans = "T";
            }
            else if (b == "C")
            {
                ans = "G";
            }
            else if (b == "G")
            {
                ans = "C";
            }
            else if (b == "T")
            {
                ans = "A";
            }

            Console.WriteLine(ans);
        }
    }
}