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

namespace ABC122_A_Double_Helix
{
	class Program
	{
		static void Main(string[] args)
		{
			Dictionary<char, char> valuePairs = new Dictionary<char, char>()
			{
				{'A', 'T' },
				{'T', 'A' },
				{'C', 'G' },
				{'G', 'C' }
			};

			char input = char.Parse(Console.ReadLine());
			Console.WriteLine(valuePairs[input]);
		}
	}
}