#include"bits/stdc++.h"
using namespace std;
#define LL long long
#define PB push_back
#define MP make_pair

//幾何ライブラリ from 螺旋本
#define EPS (1e-10) //10^(-10)
#define equals(a, b) (fabs((a) - (b)) < EPS)

//点
struct Point {
	double x, y;

	Point(double x = 0, double y = 0) : x(x), y(y) {}

	Point operator + (Point p) { return Point(x+p.x, y+p.y); }
	Point operator - (Point p) { return Point(x-p.x, y-p.y); }
	Point operator * (double a) { return Point(a*x, a*y); }
	Point operator / (double a) { return Point(x/a, y/a); }

	double abs() { return sqrt(norm()); }
	double norm() { return x*x + y*y; }

	bool operator < (const Point& p) const { return x != p.x ? x < p.x : y < p.y; }
	bool operator == (const Point& p) const { return fabs(x-p.x) < EPS && fabs(y-p.y) < EPS; }
};

//ベクトル
typedef Point Vector;
double dot(Vector a, Vector b) { return a.x* b.x + a.y*b.y; }
double cross(Vector a, Vector b) { return a.x* b.y - a.y*b.x; }

//線分
struct Segment { Point p1, p2; };

//直行判定
bool isOrthogonal(Vector a, Vector b) { return equals(dot(a, b), 0.0); }
bool isOrthogonal(Point a1, Point a2, Point b1, Point b2) { return isOrthogonal(a1-a2, b1-b2); }
bool isOrthogonal(Segment s1, Segment s2) { return equals(dot(s1.p2-s1.p1, s2.p2-s2.p1), 0.0); }

//平行判定
bool isParallel(Vector a, Vector b) { return equals(cross(a, b), 0.0); }
bool isParallel(Point a1, Point a2, Point b1, Point b2) { return isParallel(a1-a2, b1-b2); }
bool isParallel(Segment s1, Segment s2) { return equals(cross(s1.p2-s1.p1, s2.p2-s2.p1), 0.0); }

//3点の関係判定
static const int COUNTER_CLOCKWISE = 1;
static const int CLOCKWISE = -1;
static const int ONLINE_BACK = 2;
static const int ONLINE_FRONT = -2;
static const int ON_SEGMENT = 0;
int ccw(Point p0, Point p1, Point p2){
	Vector a = p1 - p0;
	Vector b = p2 - p0;
	if(cross(a, b) > EPS) return COUNTER_CLOCKWISE;
	if(cross(a, b) < -EPS) return CLOCKWISE;
	if(dot(a, b) < -EPS) return ONLINE_BACK;
	if(a.norm() < b.norm()) return ONLINE_FRONT;
	return ON_SEGMENT;
}

//交差判定
bool intersect(Point p1, Point p2, Point p3, Point p4){
	return (ccw(p1, p2, p3) * ccw(p1, p2, p4) <= 0 && ccw(p3, p4, p1) * ccw(p3, p4, p2) <= 0);
}
bool intersect(Segment s1, Segment s2){
	return intersect(s1.p1, s1.p2, s2.p1, s2.p2);
}

//Union-Find木(ランク有り)
struct UnionFind{
private:
	vector<int> parent;
	vector<int> rank;
public:
	void init(int N){ //初期化する O(N)
		parent.clear();
		rank.clear();
		for(int i=0; i<N; i++) parent.push_back(i);
		for(int i=0; i<N; i++) rank.push_back(0);
	}
	int root(int a){ //親を返す O(log N)
		if(parent[a] == a) return a;
		return parent[a] = root(parent[a]);
	}
	void unite(int a, int b){ //木を併合する O(log N)
		int rootA = root(a);
		int rootB = root(b);
		if(rootA == rootB) return;
		if(rank[rootA] < rank[rootB]) parent[rootA] = rootB;
		else{
			parent[rootB] = rootA;
			if(rank[rootA] == rank[rootB]) rank[rootA]++;
		}
	}
	bool same(int a, int b){ //属する木が同じかを返す O(log N)
		return root(a) == root(b);
	}
};

int V, R;
Point p[100];
pair<double,pair<int,int>> edge[1000];
double dist(int i, int j){
	return (p[i]-p[j]).abs();
}
pair<Point, int> P[100];
UnionFind uf;
int main(){
	cout << setprecision(16);
	cin >> V >> R;
	for(int i=0; i<V; i++){
		cin >> p[i].x >> p[i].y;
		P[i] ={ p[i],i };
	}
	sort(P, P+V);
	for(int i=0; i<R; i++){
		int s, t;
		cin >> s >> t;
		s--; t--;
		edge[i] ={ dist(s, t),{s,t} };
	}
	sort(edge, edge+R);

	//凸包
	int k = 0;
	vector<int> ans;
	for(int i=0; i<V; i++){
		while(k > 1 && ccw(p[ans[k-2]], p[ans[k-1]], P[i].first) == CLOCKWISE){
			k--;
			ans.pop_back();
		}
		ans.PB(P[i].second);
		k++;
	}
	for(int i=V-2, t=k; i>=0; i--){
		while(k > t && ccw(p[ans[k-2]], p[ans[k-1]], P[i].first) == CLOCKWISE){
			k--;
			ans.pop_back();
		}
		ans.PB(P[i].second);
		k++;
	}

	//最小全域木
	double cost = 0;
	uf.init(V);
	for(int i=0; i+1<ans.size(); i++){
		cost += (p[ans[i]]-p[ans[i+1]]).abs();
		uf.unite(ans[i], ans[i+1]);
		//cout << ans[i] << endl;
	}
	
	for(int i=0; i<R; i++){
		if(!uf.same(edge[i].second.first, edge[i].second.second)){
			uf.unite(edge[i].second.first, edge[i].second.second);
			cost += edge[i].first;
		}
	}

	cout << cost << endl;
}


Measured memory_bytes: 3300