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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

'use strict'
function main(i) {
  i = i.trim().split(' ')
  const Y = 2019
  const R = Number(i[1])
  const L = Number(i[0])
  const diff = R - L

  const hasDivisible = diff - (R % Y)
  if (hasDivisible >= 0) {
    console.log(0)
  } else {
    let ans = -1
    for (let i = L; i < R; i++) {
      let n = (i * (i + 1)) % Y
      if (ans === -1 || n < ans) ans = n
    }
    console.log(ans)
  }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));