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"
	"math"
)

func main() {
	input := scanNums(2)
	L := int64(input[0])
	R := int64(input[1])

	var minNum int64 = math.MaxInt64
	for i := L; i <= R; i++ {
		for j := i+1; j <= R; j++ {
			minNum = minInt64(minNum, (i*j)%2019)
			if minNum == 0 {
				fmt.Print(minNum)
				return
			}
		}
	}
	fmt.Print(minNum)
	return
}

func minInt64(x, y int64) int64 {
	if x < y {
		return x
	}
	return y
}
func scanNums(len int) (nums []int) {
	var num int
	for i := 0; i < len; i++ {
		fmt.Scan(&num)
		nums = append(nums, num)
	}
	return
}