#include<bits/stdc++.h>
using namespace std;
struct zb{
	int x,y;
};
int main(){
	struct zb dian[3];
	float d[3],sum=0;
	for(int i=0;i<3;i++){
		cin>>dian[i].x>>dian[i].y;
	}
	d[0]=sqrt((dian[0].x-dian[1].x)^2+(dian[0].y-dian[1].y)^2);
	d[1]=sqrt(((dian[0].x-dian[2].x)^2)+((dian[0].y-dian[2].y)^2));
	d[2]=sqrt(((dian[1].x-dian[2].x)^2)+((dian[1].y-dian[2].y)^2));
	for(int j=0;j<3;j++){
		sum=sum+d[j];
	}
	printf("%.2lf",sum);
	return 0;
}