#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;

int main(){
	double a1,a2,b1,b2,c1,c2;
	//scanf("%lflf%lf%lf%lf%lf",&a1,&a2,&b1,&b2,&c1,&c2);
	cin>>a1>>a2>>b1>>b2>>c1>>c2;
	double s=sqrt((a1-b1)*(a1-b1)+(a2-b2)*(a2-b2))+sqrt((b1-c1)*(b1-c1)+(b2-c2)*(b2-c2))+sqrt((a1-c1)*(a1-c1)+(a2-c2)*(a2-c2));
	printf("%.2lf\n",s);
	return 0;
}

如上，cin无问题，scanf莫名结果都为0，是吧空格读上了吗？