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 Julia (0.5.0) (judge verdict: Accepted)

parseint(x) = parse(Int, x)
readints() = map(parseint, readline() |> split)

function main()
    l, r = readints()
    if r - l >= 2018
        println(0)
    else
        ans = 2019
        for i = l:r-1, j = i+1:r
            ans = min(ans, (i * j) % 2019)
        end
        println(ans)
    end
end

main()