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 Haskell (GHC 7.10.3) (judge verdict: Wrong Answer)

toInt :: (String -> Int)
toInt x = read x ::Int

main = do
    x <- getLine
    let [l, r] = (map$toInt)$words x
    let i = if (r - l) >= abs (l - 2019)
        then
            2019
        else
            l
    let j = if (i - l) >= 2019
        then
            2019 * (l `div` 2019)
        else
            i + 1
    print ((i * j) `mod` 2019)