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;

pub fn read_stdin() -> String {
    let mut s = String::new();
    ::std::io::stdin().read_to_string(&mut s).unwrap();
    s
}

fn main() {
    let source = read_stdin();
    let mut iter = source.split_whitespace();
    let c: char = iter.next().unwrap().chars().next().unwrap();

    let result = match c {
        'A' => 'T',
        'T' => 'A',
        'C' => 'G',
        'G' => 'C',
        _ => 'Z',
    };

    println!("{}", result);
}