Problem:
Score: 100 points

Problem Statement

Takahashi is solving quizzes. He has easily solved all but the last one.

The last quiz has three choices: 1, 2, and 3.

With his supernatural power, Takahashi has found out that the choices A and B are both wrong.

Print the correct choice for this problem.

Constraints

Each of the numbers A and B is 1, 2, or 3.

A and B are different.

Input

Input is given from Standard Input in the following format:

A
B

Output

Print the correct choice.

Sample Input 1

3
1

Sample Output 1

2

When we know 3 and 1 are both wrong, the correct choice is 2.

Sample Input 2

1
2

Sample Output 2

3

Solution in Rust (1.42.0) (judge verdict: Accepted)

use std::collections::HashSet;

fn main() {
    let wa1 = read_line_as_value::<u8>();
    let wa2 = read_line_as_value::<u8>();
    // println!("{} {}", wa1, wa2);
    let mut set: HashSet<u8> = [1, 2, 3].iter().cloned().collect();
    set.remove(&wa1);
    set.remove(&wa2);
    println!("{}", set.iter().next().unwrap())
}

fn read_line_as_value<T: std::str::FromStr>() -> T {
    let mut input = String::new();
    let res = std::io::stdin().read_line(&mut input);
    if let Err(error) = res {
        panic!("io error at stdin.read_line: {}", error);
    };
    match input.trim().parse() {
        Ok(val) => val,
        _ => panic!("error while parsing input: {}", input)
    }
}