using namespace std;

// 计算两点间的距离
double dis(double x1, double y1, double x2, double y2) {
    double ans;
    // 计算两点间距离的公式
    ans = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
    ans = sqrt(ans);
    // 也可以使用 pow 函数来计算
    // ans = sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2)); 
    return ans;
}

int main() {
    double x1, x2, x3, y1, y2, y3, ab, ac, bc, ans;
    // 输入三个点的坐标
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    // 计算三角形三条边的长度
    ab = dis(x1, y1, x2, y2);
    ac = dis(x1, y1, x3, y3);
    bc = dis(x2, y2, x3, y3);
    // 计算三角形的周长
    ans = ab + ac + bc;
    // 输出周长，保留两位小数
    printf("%.2f", ans);
    return 0;
}

*#include<bits/stdc++.h> using namespace std; double b(double x1,double y1,double x2,double y2){ double t1=pow (x2-x1,2); double t2=pow (y2-y1,2); return sqrt(t1+t2); } int main(){ double x1,x2,y1,y2,x3,y3,sss=0; cin>>x1>>y1>>x2>>y2>>x3>>y3; sss+=b( x1, y1, x2, y2); sss+=b( x3, y3, x2, y2); sss+=b( x1, y1, x3, y3); printf("%.1lf",sss); return 0; }

#include<bits/stdc++.h> using namespace std; double dist(double x1,double y1,double x2,double y2){ double t1=(x1-x2)(x1-x2); double t2=(y1-y2)(y1-y2); return sqrt(t1+t2); } int main(){ double x1,y1,x2,y2,x3,y3,ans=0; cin>>x1>>y1>>x2>>y2>>x3>>y3; ans=ans+dist(x1,y1,x2,y2); ans=ans+dist(x1,y1,x3,y3); ans=ans+dist(x2,y2,x3,y3); printf("%.2lf",ans); return 0; }