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#include <bits/stdc++.h>
#include <math.h>
using namespace std;

int main()
{
    int x1,x2,x3,y1,y2,y3;
    //scanf("%d %d\n%d %d\n%d %d",x1,y1,x2,y2,x3,y3);
    cin>>x1>>y1>>x2>>y2>>x3>>y3;
    double s1=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
    double s2=sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
    double s3=sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));

    double c=s1+s2+s3;
    //printf("s1=%.2f s2=%.2f s3=%.2f\n",s1,s2,s3);
    printf("%.2f",c);

    return 0;
}

@JmBecca