import java.util.Scanner;
public class Demo_1{
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter x1 and y1: ");
        System.out.print("Enter x2 and y2: ");
        double b=input.nextDouble();
        double d=input.nextDouble();
        double a=input.nextDouble();
        double c=input.nextDouble();
                
        double  y= (b-a)*(b-a)+(d-c)*(d-c);
        double distance = Math.pow(y, 0.5);
        System.out.print("The distance the two points is " + distance);
    }
}