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 C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        // 入力
        long[] a = Console.ReadLine().Split().Select(long.Parse).ToArray();
        long l = a[0];
        long r = a[1];

        long ans = 2019;
        long mod = 2019;
        //組み合わせ
        for (long i = l; i <= r; i++)
        {
            for (long j = i+1; j <= r; j++)
            {
                ans = Math.Min(ans , i*j%mod);
            }   
        }

        Console.WriteLine(ans);
       
    }

 
}