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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Program
{
	class Program
	{
		static void Main(string[] args)
		{
			var lr = Console.ReadLine().Split(' ');
			var l = int.Parse(lr[0]);
			var r = int.Parse(lr[1]);

			if(r - l >= 2019)
			{
				Console.WriteLine(0);
			}
			else
			{
				var minValue = int.MaxValue;

				for (int i = l; i < r; i++)
				{
					for (int j = i + 1; j <= r; j++)
					{
						var ij = i * j;
						var result = ij % 2019;

						if (minValue > result)
						{
							minValue = result;
						}
					}
				}

				Console.WriteLine(minValue);
			}
		}
	}
}