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;

namespace AtCoderBeginner122A
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] Line = Console.ReadLine().Split(' ');
            string b = Line[0];
            switch (b[0])
            {
                case 'A':
                    Console.WriteLine('T');
                    break;
                case 'T':
                    Console.WriteLine('A');
                    break;
                case 'G':
                    Console.WriteLine('C');
                    break;
                case 'C':
                    Console.WriteLine('G');
                    break;
            }
            //int N = int.Parse(Line[0]);
        }
    }
}