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::*;
use std::str::FromStr;
use std::num::*;

fn main() {
    let mut b: String = read();
    let mut ans: String = "".to_string();
    if b == "A" {
        ans = "T".to_string();
    }else if b == "T" {
        ans = "A".to_string();
    }else if b == "C" {
        ans = "G".to_string();
    }else{
        ans = "C".to_string();
    }
    println!("{}", ans);
}
fn read<T: FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
        .map(|e| e.parse().ok().unwrap()).collect()
}

fn read_vec2<T: FromStr>(n: u32) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}