import java.util.Scanner;
public class perimeterOfSquare
{
    public static void main(String args[])
    {
        Scanner sc=new Scanner(System.in);
        System.out.println("Enter a length of square");
        double a=sc.nextDouble();

        /*Formula of perimeter of square =4*(length of square)*/
        double perimeter=4*a;
        System.out.println("perimeter of square="+perimeter);
     }
}