/*
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*/

#include <bits/stdc++.h>
#include <functional>
#include <iomanip>
using namespace std;
    
#define int long long
#define pb push_back
#define F first
#define S second
#define FOR(i,a,b) for(int (i)=(a);(i)<(b);(i)++)
#define rep(i,n) FOR(i,0,n)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define ve vector
#define vi vector<int>
#define vp vector<pair<int,int>>
#define vvi vector<vector<int>>

template<typename T> using pq = priority_queue<T,vector<T>,greater<T>>; 
using ll = long long;
ll INF = LLONG_MAX / 4000 - 100;
ll mod = 1e9 + 7;
int dx[] = {-1,0,1,0}, dy[] = {0,1,0,-1};
vector<ll> prime;
    
class fact {
public:
    int fmod = 1e9+7;
    vector<int> fac, inv;
    fact (int n, int Mod = 1e9+7) {
        fmod = Mod;
        fac = vector<int>(n,0);
        inv = vector<int>(n,0);
        fac[0] = 1; for (int i = 1; i < n; i++) fac[i] = fac[i-1] * i % fmod;
        for (int i = 0;i < n;i++) inv[i] = fact::POW(fac[i],fmod-2);
    }
    ll nCr(ll n, ll r) {if(n < r) return 0; return (fac[n] * inv[r] % fmod) * inv[n-r] % fmod;}
    ll POW(ll a, ll b) {ll c = 1; while (b > 0) {if (b & 1) {c = a * c%fmod;}a = a * a%fmod; b >>= 1;}return c;}
    inline int operator [] (int i) {return fac[i];}
};
    
template <class T = ll> T in() {T x; cin >> x; return (x);}
void DEBUG(vector<int> a) {for(int i=0;i<a.size();i++)cout<<a[i]<<" ";cout<<endl;}
void EMP(int x) {cout<<"!!!"<<x<<"!!!"<<endl;}
ll GCD(ll a, ll b) {ll c; while (b != 0) {c = a % b; a = b; b = c;}return a;}
ll LCM(ll a, ll b) {return (a / GCD(a, b)) * (b / GCD(a, b)) * GCD(a, b);}
ll POW(ll a, ll b) {ll c = 1; while (b > 0) {if (b & 1) {c = a * c%mod;}a = a * a%mod; b >>= 1;}return c;}
void PRI(ll n) {bool a[n + 1LL]; for (int i = 0; i < n + 1LL; i++) {a[i] = 1LL;}for (int i = 2; i < n + 1LL; i++) {if (a[i]) {prime.pb(i); ll b = i; while (b <= n) {a[b] = 0; b += i;}}}}
template <typename T> T chmin(T& a, T b) {if(a>b)a=b;return a;}
template <typename T> T chmax(T& a, T b) {if(a<b)a=b;return b;}
bool isSqrt(ll a) {return pow(sqrt(a),2) == a ? 1 : 0;}
void YesNo(bool a) {if (a) cout << "Yes"; else cout << "No"; cout << endl;}
void yesno(bool a) {if (a) cout << "yes"; else cout << "no"; cout << endl;}
void YESNO(bool a) {if (a) cout << "YES"; else cout << "NO"; cout << endl;}
double dis(int x1, int x2, int y1, int y2) {
    return sqrt((double)abs(x1-x2)*(double)abs(x1-x2)+(double)abs(y1-y2)*(double)abs(y1-y2));
}

double EPS = 1e-10;

double add(double a, double b) {
    if (abs(a + b) < EPS * (abs(a) + abs(b))) return 0;
    return a + b;
}

struct P {
    int id = -1;
    double x, y;
    P() {}
    P(double x, double y): x(x), y(y) {}
    P(double x, double y, int id): x(x), y(y), id(id) {}
    P operator + (P p) {
        return P(add(x, p.x), add(y, p.y));
    }
    P operator - (P p) {
        return P(add(x, -p.x), add(y, -p.y));
    }
    P operator * (double d) {
        return P(x * d, y * d);
    }
    double dot(P p) {
        return add(x * p.x, y*p.y);
    }
    double det(P p) {
        return add(x * p.y, -y * p.x);
    }
    double dist(P p) {
        return abs(sqrt((p.x - x) * (p.x - x) + (p.y - y) * (p.y - y)));
    }
};

bool cmp_x(P p, P q) {
    if (p.x != q.x) return p.x < q.x;
    return p.y < q.y;
}

vector<P> convex_hull(vector<P> ps, int n) {
    sort(ps.begin(), ps.end(), cmp_x);
    int k = 0;
    vector<P> qs(n * 2);

    for (int i = 0; i < n; i++) {
        while (k > 1 && (qs[k-1] - qs[k-2]).det(ps[i] - qs[k-1]) <= 0) k--;
        qs[k++] = ps[i];
    }

    for (int i = n - 2, t = k; i >= 0; i--) {
        while (k > t && (qs[k-1] - qs[k-2]).det(ps[i] - qs[k-1]) <= 0) k--;
        qs[k++] = ps[i];
    }
    qs.resize(k-1);
    return qs;
}

class UnionFind {
private:
	vector<int> par;
public:
	UnionFind(int N) { par = vector<int>(N, -1); }
	int find(int x);
	ll size(int x);
	void unite(int x, int y);
	bool same(int x, int y);
};

int UnionFind::find(int x) {
	if (par[x] < 0) return x;
	else return par[x] = find(par[x]);
}
 
ll UnionFind::size(int x) {
	return -par[find(x)];
}
 
void UnionFind::unite(int x, int y) {
	x = find(x);
	y = find(y);
 	if (x == y) return;
	//大きい方に小さい方をくっ付ける
	if (size(x) < size(y)) swap(x, y);
	par[x] += par[y];
	par[y] = x;
}
 
bool UnionFind::same(int x, int y) {
	x = find(x);
	y = find(y);
	return x == y;
}

vector<vector<pair<int, double>>> edge;
vector<P> vil;

bool solve() {
    int v, r; cin >> v >> r;
    rep (i, v) {
        int x, y; cin >> x >> y;
        vil.pb(P(x, y, i));
    }
    edge = vector<vector<pair<int, double>>>(v);
    rep (i, r) {
        int s, t; cin >> s >> t; --s, --t;
        double d = vil[s].dist(vil[t]);
        edge[s].pb({t, d});
    }

    vector<P> ch = convex_hull(vil, v);

    UnionFind uf(v);
    pq<pair<double, pair<int, int>>> q;
    rep (i, ch.size()) {
        if (i != 0) {
            uf.unite(ch[i].id, ch[i-1].id);
        }
    }
    rep (i, v) {
        for (auto&& to : edge[i]) {
            q.push({to.second, {to.first, i}});
        }
    }

    vector<pair<double, pair<int, int>>> mst;
    while (!q.empty()) {
        auto cand = q.top(); q.pop();
        int s = cand.second.first, t = cand.second.second;
        if (!uf.same(s, t)) {
            mst.pb({cand.first, {s, t}});
            uf.unite(s, t);
        }
    }

    double ans = 0;
    rep (i, mst.size()) {
        ans += mst[i].first;
    }

    rep (i, ch.size()) {
        int idx = (i + 1) % ch.size();
        ans += ch[idx].dist(ch[i]);
    }

    cout << fixed << setprecision(10);
    cout << ans << endl;
}

signed main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
}



Measured memory_bytes: 3320