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)

use std::cmp;

macro_rules! input {
    // ?
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };

    // stdinの生成 値の読み込み開始
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        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_rules! input_inner {
    // ?
    ($next:expr) => {};
    // ?
    ($next:expr, ) => {};

    // 変数名:型の読み込みの繰り返し
    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

macro_rules! read_value {
    // 値を読み込むベース 型,の繰り返し
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    // 配列の読み込み
    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    // 文字列Vec<char>の読み込み
    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    // usize1?の読み込み
    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    // 指定した型で読み込み
    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}


fn main() {
    input! {
        a:isize,
        b:isize,
    };

    println!("{}", solve(a, b));
}

fn solve(a: isize, b: isize) -> isize {
    let plus: isize = a + b;
    let minus: isize = a - b;
    let kakeru: isize = a * b;

    return cmp::max(plus, cmp::max(minus, kakeru));
}
macro_rules! tests {
    ($($test_name:ident:$name:ident($( $args:expr ),*) => $expected:expr,)*) => {
        mod tests {
            $(
                #[test]
                fn $test_name() {
                    assert_eq!($expected,super::$name($($args),*));
                }
            )*
        }
    }
}


tests! {
    //テスト名:[引数]=>expected
    test1:solve(2,4) => 8,
    test2:solve(2,-4) => 6,
    test3:solve(0,0) => 0,
}