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)

fun main(args : Array<String>) {
    val (L, R) = readLine()!!.split(" ").map { it.toLong() }
    val MOD = 2019
    val l = (L % MOD).toInt()
    val r = (R % MOD).toInt()


    val candidates = mutableListOf<Int>()
    var i = l
    candidates.add(i)
    while (i < r) {
        i = (i+1).mod(MOD)
        candidates.add(i)
    }

    val size = candidates.size

    if (size <= 1) {
        println(0)
        return
    }

    var answer = Int.MAX_VALUE
    candidates.sort()
    (0..(size - 1)).forEach { i ->
        ((i+1)..(size - 1)).forEach { j ->
            answer = Math.min(answer, (candidates[i] * candidates[j]).mod(2019))
        }
    }

    if (candidates.contains(3) && candidates.contains(673)) {
        println(0)
        return
    }

    println(answer)
}