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;

class Program{

  static string ans;

  static int Main() {

    string nyu = Console.ReadLine();

    // ここまで入力

    if (nyu == "A") {
      ans = "T";
    } else if (nyu == "T") {
      ans = "A";
    } else if (nyu == "C") {
      ans = "G";
    } else if (nyu == "G") {
      ans = "C";
    }

    Console.WriteLine("{0}", ans);

    return 0;
  }

}