View Code of Problem 18

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        while (scanner.hasNext()){
            int n= Integer.parseInt(scanner.nextLine());
            int m=n/2;
            int sum=(m-1)*m/2;
            sum+=(n-m)*(n-m-1)/2;
            System.out.println(sum);
        }
    }
}