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 Scala (2.11.7) (judge verdict: Time Limit Exceeded)

import scala.io.StdIn

object Main extends App {
  val Array(l, r)  = StdIn.readLine().split(" ").map(_.toInt)

  val lm = l % 2019
  val lr = (l / 2019).floor
  val rr = (r / 2019).floor

  
  if (r % 2019 < lm) {
    println(0)
  } else if (lr != rr) {
    println(0)
  } else {
    val rm = r % 2019
    if (lm == 0 || rm == 0)
      println(0)
    else
      println((lm to rm).combinations(2).map{ i => (i(0) * i(1)) % 2019 }.min)
  }
}