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# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.ExceptionServices;
using System.Runtime.InteropServices;
using System.Text;


namespace AtCoderDotNetCore
{
	class Program
	{
		static void Main(string[] args)
		{
			Question.Exec();
		}
	}

	public static class Question
	{
		public static void Exec()
		{
			Dictionary<char, char> dict = new Dictionary<char, char>();
			dict.Add('A', 'T');
			dict.Add('C', 'G');
			dict.Add('G', 'C');
			dict.Add('T', 'A');
			char c = Console.ReadLine()[0];
			
			Console.WriteLine($"{dict[c]}");
		}
	}
}