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;

class Problem
{
    public static void Main()
    {
        char[] a = { 'A', 'T', 'C', 'G' };
        char[] b = { 'T', 'A', 'G', 'C' };
        string s = Console.ReadLine();
        for(int i=0; i < 4; i++)
        {
            if (s[0] == a[i])
            {
                Console.Write(b[i]);
            }
        }
    }
    
}