样例不过

#include<iostream>
#include<iomanip>
#include<cmath>
using namespace std;
int main()
{
    int x1=0,x2=0,x3=0,y1=0,y2=0,y3=0;
    double c1=0,c2=0,c3=0,tot=0;
    cin>>x1>>y1>>x2>>y2>>x3>>y3;
    c1=sqrt(abs(x2-x1)*abs(x2-x1)+abs(y2-y1)*abs(y2-y1));
    c2=sqrt(abs(x2-x1)*abs(x2-x1)+abs(y2-y1)*abs(y2-y1));
    c3=sqrt(abs(x2-x1)*abs(x2-x1)+abs(y2-y1)*abs(y2-y1));
    tot=c1+c2+c3;
    cout<<fixed<<setprecision(2)<<tot;
    cout<<endl;
    return 0;
}