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: Runtime Error)

using System;

class Program
{
  static void Main(string[] args)
  {
    // get a char
    char a = Convert.ToChar(args[0]);
    char val = 'C';
    if (a == 'A')
      val = 'T';
    else if (a == 'T')
      val = 'A';
    else if (a == 'C')
      val = 'G';
    else
      val = 'C';
    //output
    Console.WriteLine(val);
  }
}