#include<bits/stdc++.h>
using namespace std;
int main(){
	double x1,y1,x2,y2,x3,y3,dis1,dis2,dis3,ans=0;
	scanf("%lf%lf%lf%%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
    dis1=sqrt((abs(x2-x1)*abs(x2-x1))+(abs(y2-y1)*abs(y2-y1)));
    dis2=sqrt((abs(x3-x2)*abs(x3-x2))+(abs(y3-y2)*abs(y3-y2)));
    dis3=sqrt((abs(x1-x3)*abs(x1-x3))+(abs(y1-y3)*abs(y1-y3)));
    ans=dis1+dis2+dis3;
	printf("%.2f",ans);
	return 0;
}