#include <bits/stdc++.h>

using namespace std;
ifstream fin("retea2.in");
ofstream fout("retea2.out");
const double mare = 100002;
void dijkstra(int start);
double distanta(pair<int, int> a, pair<int, int> b);
struct ura
{
    int nod;
    double cost;
    bool operator < (const ura &aux) const
    {
        return cost > aux.cost;
    }
};

priority_queue<ura> q;
double d[4001], suma;
int n, m;
bool viz[4001];
pair<int, int> coord[4001];

int main()
{
    fin>>n>>m;

    for(int i = 1; i <= n+m; ++i)
        d[i] = mare;

    for(int i = 1; i <= n; ++i)//centrale
    {
        fin>>coord[i].first>>coord[i].second;
        d[i] = 0;
        q.push({i, 0});
    }
    for(int i = n+1; i <= n+m; ++i)
    {
        fin>>coord[i].first>>coord[i].second;
    }
    dijkstra(1);
    fout<<fixed<<setprecision(6)<<suma;






    return 0;
}

void dijkstra(int start)
{

    while(!q.empty())
    {
        int nod = q.top().nod;
        double crtcost = q.top().cost;
        q.pop();
        if(viz[nod] || crtcost != d[nod])
            continue;
        viz[nod] = 1;
        suma += crtcost;
        for(int i = 1; i <= n+m; ++i)
        {
            if(viz[i])
                continue;
            double dist = distanta(coord[nod], coord[i]);
            if(d[i] > dist)
            {
                d[i] = dist;
                q.push({i, dist});
            }
        }
    }
}

double distanta(pair<int, int> a, pair<int, int> b)
{
    int c1 = (a.first - b.first) * (a.first - b.first);
    int c2 = (a.second - b.second) * (a.second - b.second);
    return sqrt(c1 + c2);
}