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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

import java.math.BigDecimal
import java.util.*

fun main(args: Array<String>) {
    val sc = java.util.Scanner(System.`in`)
    val L = sc.nextLong()
    val R = sc.nextLong()

    var min: Long = R % 2019
    (L until R).forEach {
        min = Math.min(min, it % 2019)
        if (min == 0L) {
            println(0)
            return
        }
    }
    val min0 = min

    min = R % 673
    run loop@ {
        (L until R).forEach {
            min = Math.min(min, it % 673)
            if (min == 0L) {

                min = R % 3
                (L until R).forEach {
                    min = Math.min(min, it % 3)
                    if (min == 0L) {
                        println(0)
                        return
                    }
                }

                return@loop
            }
        }
    }

    println(min0 * (min0 + 1L))
}