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";
    
const main = arg => {
    arg = arg.trim().split("\n");
    const L = parseInt(arg[0].split(" ")[0]);
    const R = parseInt(arg[0].split(" ")[1]);
    
    let answer = L;
    
    for(let i=L; i<=R; i++) {
        // ぴったりならそこ
        if(i % 2019 === 0) {
            answer = i;
            break;
        }
    }

    console.log((answer * (answer + 1)) % 2019);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));