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 Program
{
	class test
    {
    	static void Main()
        {
          	string[] cs = new string[]{"A","C","G","T"};
        	string s = Console.ReadLine();
          	if(s == cs[0]) {
          		Console.WriteLine(cs[3]);
            }
            if(s == cs[1]) {
          		Console.WriteLine(cs[2]);
            }
            if(s == cs[2]) {
          		Console.WriteLine(cs[1]);
            }
            if(s == cs[3]) {
          		Console.WriteLine(cs[0]);
            }
        }
    }
}