import java.util.Scanner;
 class point {
	private double x,y;
	public point(double x,double y) {
		this.x=x;
		this.y=y;
	}
	public double getx() {
		return x;
	}
	public double gety() {
		return y;
	}

}

public class Main {
	public static void main(String []args) {
		point[] ppp= new point[4];
		
		for(int i=0;i<3;i++) {
			Scanner sc=new Scanner(System.in);
			int x1=sc.nextInt();
			int x2=sc.nextInt();
			ppp[i]=new point(x1,x2);
			//System.out.print(ppp[i].getx());
			//System.out.print(ppp[1].gety());
			
		}
		double distance,d1,d2,d3;
		d1=Math.sqrt((ppp[0].getx()-ppp[2].getx())*(ppp[0].getx()-ppp[2].getx())+(ppp[0].gety()-ppp[2].gety())*(ppp[0].gety()-ppp[2].gety()));
		d2=Math.sqrt((ppp[1].getx()-ppp[0].getx())*(ppp[1].getx()-ppp[0].getx())+(ppp[1].gety()-ppp[0].gety())*(ppp[1].gety()-ppp[0].gety()));
		d3=Math.sqrt((ppp[1].getx()-ppp[2].getx())*(ppp[1].getx()-ppp[2].getx())+(ppp[1].gety()-ppp[2].gety())*(ppp[1].gety()-ppp[2].gety()));
		distance=d1+d2+d3;
		System.out.print(String.format("%.2f", distance));
		
	}
	
	

}