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.Diagnostics;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace AtCoder
{
    public class QuestionA
    {
        public static void Main(string[] args)
        {
            string result = "";

            string s = Console.ReadLine();

			switch(s){
                case "A":
                    result = "T";
                    break;
                case "C":
                    result = "G";
                    break;
                case "G":
                    result = "C";
                    break;
                case "T":
                    result = "A";
                    break;
            }
            Console.WriteLine(result);
        }
    }
}