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 <iostream>
#include <vector>  
#include <math.h>
using namespace std;
 
int main(void){
  int l;
  vector <int> a;
    while(cin>>l){
        a.push_back(l);
    }
  int L = a[0];
  int R = a[1];
  int tmp=2019;
 
  if (R-L >= 2019){
  tmp =0;
  }  
  else if(L==0){
    tmp = 1;
    for (int i = L+1;i < R;++i){
      for (int ii = L+2;ii <= R;++ii){
        int diff =(i*ii)%2019;
        if (tmp > diff && diff>0){
          tmp = diff;
        }
      }
    }
  }
  else{
    for (int i = L;i < R;++i){
      for (int ii = L+1;ii <= R;++ii){
        int diff =(i*ii)%2019;
        if (tmp > diff && diff >0){
          tmp = diff;
        }
      }
    }
  }  
  cout << tmp;
}