Exercise1_3.java

import java.util.Scanner;
public class Exercise1_3 {
       public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n=sc.nextInt();
		int sum=0,t;
 //Use for or while loop do the operation
		for(int i=0;i<=n;i++)
		{
			t = 2*(i-1);
			if(t%3 == 0)
			{
				sum += t;
			}
		}
		System.out.println(sum);
	}
}