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 System.Text;
using System.Threading.Tasks;

namespace atcoder01a
{
    class Program
    {
        static void Main(string[] args)
        {
            string a = "A";
            string c = "C";
            string g = "G";
            string t = "T";
            string b =Console.ReadLine();
            if (b == a)
            {
                Console.WriteLine(t);
            }
            else if (b == c)
            {
                Console.WriteLine(g);
            }
            else if (b == t)
            {
                Console.WriteLine(a);
            }
            else if (b == g)
            {
                Console.WriteLine(c);
            }
            else return;
        }
    }
}