#include<bits/stdc++.h>
using namespace std;
int main(){
    int x1,x2,x3,y1,y2,y3;
    double d1_2,d2_3,d1_3,a;
	cin>>x1>>y1;
	cin>>x2>>y2;
	cin>>x3>>y3;
	d1_2=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
	d2_3=sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
	d1_3=sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
	printf("%.2lf",d1_2+d1_3+d2_3);
	return 0; 
}

错一个点