#include<iostream>
#include<cmath>
using namespace std;
double dis(double x1, double y1, double x2, double y2) {
	double d = sqrt(pow(x1-x2,2)+pow(y1-y2,2));
	return d;
}
int main() {
	double x1, y1, x2, y2, x3, y3;
	cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
	double a=dis(x1, y1,x2,y2);
	double b=dis(x2, y2,x3,y3);
	double c=dis(x3, y3,x1,y1);
	printf("%.2lf",a+b+c);
	return 0;
}