Problem:
Score : 100 points

Problem Statement

You are given two integers A and B.
Find the largest value among A+B, A-B and A \times B.

Constraints

-1000 \leq A,B \leq 1000

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B

Output

Print the largest value among A+B, A-B and A \times B.

Sample Input 1

3 1

Sample Output 1

4

3+1=4, 3-1=2 and 3 \times 1=3. The largest among them is 4.

Sample Input 2

4 -2

Sample Output 2

6

The largest is 4 - (-2) = 6.

Sample Input 3

0 0

Sample Output 3

0

Solution in Rust (1.15.1) (judge verdict: Accepted)

#[macro_use]
pub mod basic_stdin {
use std::str::FromStr;

pub fn read<T: FromStr>() -> T {
    use std::io::stdin;
    use std::io::Read;

    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed reading char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed parsing")
}

}

#[macro_export]
macro_rules! test_function {
    (func = $func:expr, $($input:expr => $output:expr),* $(,)*) => {
        $(
            assert_eq!($func(std::io::Cursor::new($input)) , $output);
        )*
    };
}

#[macro_export]
macro_rules! input_macro {
    (string = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    (reader = $s:expr, $($r:tt)*) => {
        let reader = std::io::BufReader::new($s);
        let mut bytes = std::io::Read::bytes(reader);
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

#[macro_export]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[macro_export]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    let stdin = std::io::stdin();
    let ret = solve(stdin.lock());

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

fn solve<T: std::io::Read>(reader: T) -> i64 {
    input_macro! {
        reader = reader,
        a: i64,
        b: i64,
    }

    let x = a + b;
    let y = a - b;
    let z = a * b;

    let vec = vec![x, y, z];
    vec.into_iter().max().unwrap()
}

#[cfg(test)]
mod tests {

    #[test]
    fn test_solve_function() {
        atcorder::test_function! {
            func = super::solve,
            "3 1" => 4,
        }
    }
}