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 Pascal (FPC 2.6.2) (judge verdict: Wrong Answer)

var
	L,R,ans,tmp,M,i,j:Longint;
begin
	read(L,R);
	M:=2019;
	ans:=M;
	if L+2018<=R then begin
		writeln(0);
		exit;
	end;
	for i:=L to R do begin
		for j:=1 to 10 do begin
			if i+j>R then break;
			tmp:=i mod M*(i+j)mod M;
			if ans>tmp then ans:=tmp;
			if(i-j>R)or(i-j<L)then break;
			tmp:=i mod M*(i-j)mod M;
			if ans>tmp then ans:=tmp;
		end;
	end;
	writeln(ans);
end.