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;
        using System.Linq;
        using System.Collections.Generic;
 
        public class Program
        {
            public static void Main(string[] args)
            {
            int[] input = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            string word = Console.ReadLine();
            List<int> answer = new List<int> { };
 
            for (int i = 0; i < input[1]; i++)
            {
                int[] q = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
 
                string qWord = word.Substring(q[0] - 1, q[1] - q[0] + 1);
                answer.Add((qWord.Length - qWord.Replace("AC", "").Length) / 2);
            }
 
            foreach (int a in answer) Console.WriteLine(a);
            }
        }