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: Runtime Error)

program kadai
implicit none
integer  ::  l,r
integer  ::  i,j
integer,allocatable  ::  ans(:)
integer  ::  mn


read(*,*) l,r

if (r/2019-l/2019>1) then
    write(*,*) 0
    stop
end if

l=mod(l,2019)
r=mod(r,2019)

allocate(ans(r-l))
ans=2020
do i=l,r
    do j=i+1,r
        ans(i+j-2*l)=mod(i*j,2019)
    end do
end do

mn=minval(ans)
!write(*,*) ans
write(*,*) mn,l,r

stop

end program kadai