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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repm(i, m, n) for (int i = (m); i < (int)(n); i++)
#define repr(i, n) for (int i = (n); i > 0; i--)
#define all(vec) vec.begin(), vec.end()
using namespace std;

int main(){
  int a, b;
  cin >> a >> b;
  
  int ans = 0;
  //string ans = "Yes";
  //string ans = "No";
  //string ans = "YES";
  //string ans = "NO";
  if (b - a + 1 < 2019){
    repm(i, a, b){
      repm(j, i + 1, b + 1) ans = min(ans, i * j);
    }
  }
  
  cout << ans << endl;
}