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 Rust (1.15.1) (judge verdict: Accepted)

use std::io::Read;
use std::cmp;

fn main() {
    let mut b = String::new();

    // 標準入力から全部bufに読み込む
    std::io::stdin().read_line(&mut b).expect("failed");

    let s = b.trim();
    match s {
        "A" => println!("T"),
        "T" => println!("A"),
        "C" => println!("G"),
        "G" => println!("C"),
        _ => println!("_"),
    }
}