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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.*;
import  java.util.*;
import static java.lang.System.in;

public class Main{
    static int n,m;
    static long[] head,pos;
    public static void main(String[] args)throws IOException{
        Scanner sc = new Scanner(System.in);
        //BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        //String[] buf = reader.readLine().split(" ");
        char b = sc.next().charAt(0);
        char ans;
        if(b=='A') ans = 'T';
        else if(b=='T') ans ='A';
        else if(b=='C') ans = 'G';
        else ans = 'C';
        System.out.println(ans);
    }
}