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 Go (1.6) (judge verdict: Accepted)

package main

import "fmt"

func main() {
	var l, r int
	fmt.Scan(&l, &r)

	a := l % 2019
	b := r % 2019

	if a >= b || r-l > 2019 {
		fmt.Println(0)
		return
	}
	if a < b {
		min := 10000
		for i := a; i <= b-1; i++ {
			for j := i + 1; j <= b; j++ {
				t := (i * j) % 2019
				if t < min {
					min = t
				}
			}
		}
		fmt.Println(min)
		return
	}
}