#include    <fstream>
    #include    <iostream>
    #include    <algorithm>
    #include    <math.h>
    using namespace std;
    ifstream f("desen.in");
    ofstream g("desen.out");
    const int NMax = 400005;
    pair <int,int> P[NMax];
    int N, M, Total, TT[NMax], k, RG[NMax],nr,kk;
    struct Edge
    {
        int x,y,c;
    }V[NMax];

    struct Point
    {
        int x,y;
    }puncte[NMax];

    bool Compare(Edge a, Edge b)
    {
        return a.c < b.c;
    }
    void Read()
    {
        f>> N;
        for(int i = 1; i <= N; i++)
            {
             f >> V[i].x >> V[i].y>>V[i].c;

            }
        sort(V+1, V+N+1, Compare);

    }
    int Find(int nod)
    {
        while(TT[nod] != nod)
            nod = TT[nod];
        return nod;
    }
    void Unite(int x, int y)
    {
        if(RG[x] < RG[y])
            TT[x] = y;
        if(RG[y] < RG[x])
            TT[y] = x;
        if(RG[x] == RG[y])
        {
            TT[x]=y;
            RG[y]++;
        }
    }
    void Solve()
    {
        for(int i=1;i<=nr;i++)
        {

            if(Find(V[i].x) != Find(V[i].y))
            {

                Unite(Find(V[i].x), Find(V[i].y));
                P[++k].first    =   V[i].x;
                P[k].second     =   V[i].y;
                Total           +=  V[i].c;
            }
        }
    }
    int main()
    {
        f>>N;int j;
        for(int i = 1; i <= N; i++)
            { k=0;Total=0;
             f>> puncte[i].x >> puncte[i].y;

             for(j=1;j<i;j++)
             {
              kk++;
              V[kk].x=i;
              V[kk].y=j;
              V[kk].c=sqrt(abs(puncte[i].x - puncte[j].x) * abs(puncte[i].x - puncte[j].x) + abs(puncte[i].y - puncte[j].y) * abs(puncte[i].y - puncte[j].y));

             }

        sort(V+1, V+kk+1, Compare);

        nr=kk;
        kk=0;

        for(int j = 1; j <= nr; i++)
        {
            TT[j]=j;
            RG[j]=1;
        }
        Solve();
        g << Total << "\n";
            }
        return 0;
    }