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 Fortran (gfortran v4.8.4) (judge verdict: Wrong Answer)

program main
 implicit none
 integer*8 L,R,i,j,v,mini,m
 data m /2019/
 read(*,*) L,R
 L = mod(L,m)
 R = mod(R,m)
 if(L > R) then
  write(*,*) 0
 else
  mini = 2018
  do i=L,R-1
   do j=i+1,R
    v = mod(i,m)*mod(j,m)
    v = mod(v,m)
    if(v < mini) then
     mini = v
    end if
   end do
  end do
  write(*,*) mini
 end if
end program main