import java.util.Scanner;
public class SumSeries
{
    public static void main()
    {
        int n=0,i=0;
        long sum=0,num=1;
        Scanner sc=new Scanner(System.in);
        System.out.println("ENTER THE Nth TERM");
        n=sc.nextInt();
        for(i=1;i<=n;i++)
        {
            sum=sum+num; 
            num=num+2;
        }
        System.out.println("SUM OF SERIES="+sum);
    }
}