Problem:
Score : 300 points

Problem Statement

You are given two non-negative integers L and R.
We will choose two integers i and j such that L \leq i < j \leq R.
Find the minimum possible value of (i \times j) \mbox{ mod } 2019.

Constraints

All values in input are integers.

0 \leq L < R \leq 2 \times 10^9

Input

Input is given from Standard Input in the following format:

L R

Output

Print the minimum possible value of (i \times j) \mbox{ mod } 2019 when i and j are chosen under the given condition.

Sample Input 1

2020 2040

Sample Output 1

2

When (i, j) = (2020, 2021), (i \times j) \mbox{ mod } 2019 = 2.

Sample Input 2

4 5

Sample Output 2

20

We have only one choice: (i, j) = (4, 5).

Solution in Rust (1.15.1) (judge verdict: Wrong Answer)

fn read_split<T : std::str::FromStr>() -> Vec<T> {
    let mut input = String::new();
    std::io::stdin().read_line(&mut input).unwrap();
    input.trim().split_whitespace().map(|x| x.parse().ok().unwrap()).collect()
}

fn main() {
    let inputs : Vec<i64> = read_split();
    if inputs[1] - inputs[0] >= 2019{
        println!("0");
        return;
    }
    let xx = inputs[0] / 2019;
    let a = inputs[0] - (xx * 2019);
    let b = inputs[1] - (xx * 2019);
    if a <= 2019 && b >= 2019 {
        println!("0");
        return;
    }

    let result = (a * (a + 1)) % 2019;

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