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: Wrong Answer)

object Main extends App {
  
  var a = readLine.split(" ").map(_.toInt)
  def b(c:Long,d:Long,e:Long,f:Long):Long = {
    if(d-c>2019){
      return 0
    }
    if(c+1>d) {
      return f
    } else {
      var g=if((c*(c+1))%2019<f)(c*(c+1))%2019 else f
      b(c+1,d,c*d%2019,g)
    }
  }
  print(b(a(0),a(1),2020,2020))
}