// R38740507

#include <bits/stdc++.h>

using namespace std;

int main() {
    double x1, y1, x2, y2, x3, y3;
    scanf("%lf%lf%lf%lf%lf%lf", &x1, &y1, &x2, &y2, &x3, &y3), printf("%.2lf\n", sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)) + sqrt((x2 - x3) * (x2 - x3) + (y2 - y3) * (y2 - y3)) + sqrt((x1 - x3) * (x1 - x3) + (y1 - y3) * (y1 - y3)));
    return 0;
}