Code：

#include<iostream>
#include<cmath>
using namespace std;
double dis(double x,double _x,double y,double _y)
{
    return sqrt(((_x-x)*(_x-x))+(_y-y)*(_y-y));
}
int main()
{
    int x1,x2,y1,y2,z1,z2,ans;
    ans=dis(x1,x2,y1,y2)+dis(x1,x2,z1,z2)+dis(y1,y2,z1,z2);
    printf("%.2f",ans);
    return 0;
}