/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		int n = 2005;
		int[] a = new int[n*n];
		for (int i=0; i<2005; i++) a[i] = i+1;
		for (int i=0, j=2005; i<=n-1; i+=2, j++) a[j] = a[i] + a[i+1];
		long s = 0;
		for (int i=0; i<n*n; i++) s += a[i];
		System.out.println(s);
	}
}

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

NDU=

45