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: Wrong Answer)

package main

import "fmt"

func main() {
	var l, r int
	fmt.Scan(&l, &r)
	//2019個以上ならおけ
	w := r-l+1
	if w%2019 == 0{
		fmt.Println(0)
		return
	}
	ans := 1000000000
	cnt := 1000000000
	for i:=l; i<=r ; i++ {
		//IからJの中で、2019で割り切れるるものは最小値０
		if i%2019 == 0 {
			fmt.Println(0)
			return
		}
		//範囲の中にある2019に一番近い2つの数字が答え
		cnt = i%2019
		if ans > cnt {
			ans = cnt
		}
	}
	fmt.Println(ans*(ans+1))
}