import java.io.PrintWriter;
import java.util.Scanner;

public class well2 {
    static Scanner in = new Scanner(System.in);
    static PrintWriter out = new PrintWriter(System.out, true);
    static double perimeter(int x1, int y1, int x2, int y2, int x3, int y3) {
        return (Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)) + Math.sqrt((x2 - x3) * (x2 - x3) + (y2 - y3) * (y2 - y3)) +
        		Math.sqrt((x1 - x3) * (x1 - x3) + (y1 - y3) * (y1 - y3)));
    }
    public static void main(String[] args) {
       int x1 = in.nextInt(), y1 = in.nextInt();
       int x2 = in.nextInt(), y2 = in.nextInt();
       int x3 = in.nextInt(), y3 = in.nextInt();
       double p;
       p = perimeter(x1,y1,x2,y2,x3,y3);

       out.printf("%.6f", p);
       out.close();
  }
}