0分小蒟蒻求调，求求了！！！

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