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 static System.Console;

class Program
{
    static void Main()
    {
        //var NN = ReadLine().Split().Select(int.Parse).ToArray();
        var b = ReadLine();

        switch (b)
        {
            case "A":
                WriteLine("T");
                break;
            case "T":
                WriteLine("A");
                break;
            case "C":
                WriteLine("G");
                break;
            case "G":
                WriteLine("C");
                break;
            default:
                break;
        }
    }
}