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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
const int VALUE = 2019;

int Find(const long L, const long R)
{
	int ans = VALUE;
	for (long i = L; i <= R; ++i)
	{
		for (long j = i + 1; j <= R; ++j)
		{
			ans = min(ans, static_cast<int>((i*j) % VALUE));
			if (ans == 0)
			{
				return ans;
			}
		}
	}
	return ans;
}

int main()
{
	long L, R;
	cin >> L >> R;

	cout << Find(L, R) << endl;
}