#include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)n;i++)
#define all(c) (c).begin(),(c).end()
#define pb push_back
#define dbg(...) do{cerr<<__LINE__<<": ";dbgprint(#__VA_ARGS__, __VA_ARGS__);}while(0);

using namespace std;

namespace std{template<class S,class T>struct hash<pair<S,T>>{size_t operator()(const pair<S,T>&p)const{return ((size_t)1e9+7)*hash<S>()(p.first)+hash<T>()(p.second);}};template<class T>struct hash<vector<T>>{size_t operator()(const vector<T> &v)const{size_t h=0;for(auto i : v)h=h*((size_t)1e9+7)+hash<T>()(i)+1;return h;}};}
template<class T>ostream& operator<<(ostream &os, const vector<T> &v){os<<"[ ";rep(i,v.size())os<<v[i]<<(i==v.size()-1?" ]":", ");return os;}template<class T>ostream& operator<<(ostream &os,const set<T> &v){os<<"{ "; for(const auto &i:v)os<<i<<", ";return os<<"}";}
template<class T,class U>ostream& operator<<(ostream &os,const map<T,U> &v){os<<"{";for(const auto &i:v)os<<" "<<i.first<<": "<<i.second<<",";return os<<"}";}template<class T,class U>ostream& operator<<(ostream &os,const pair<T,U> &p){return os<<"("<<p.first<<", "<<p.second<<")";}
void dbgprint(const string &fmt){cerr<<endl;}template<class H,class... T>void dbgprint(const string &fmt,const H &h,const T&... r){cerr<<fmt.substr(0,fmt.find(","))<<"= "<<h<<" ";dbgprint(fmt.substr(fmt.find(",")+1),r...);}
typedef long long ll;typedef vector<int> vi;typedef pair<int,int> pi;const int inf = (int)1e9;
const double EPS = 1e-8, INF = 1e12, PI = acos(-1.0);
typedef complex<double> P;
namespace std{
	bool operator<(const P& a, const P& b){
		return real(a) != real(b) ? real(a) < real(b) : imag(a) < imag(b);
	}
}
inline double cross(const P& a, const P& b){ return imag(conj(a)*b); }
inline double dot(const P& a, const P& b){ return real(conj(a)*b); }
struct L : public vector<P>{
	L(const P &a, const P &b) {
		push_back(a); push_back(b);
	}
};
typedef vector<P> G;
inline int ccw(P a, P b, P c) {
	b -= a; c -= a;
	if(cross(b, c) >  EPS)   return +1;      // counter clockwise
	if(cross(b, c) < -EPS)   return -1;      // clockwise
	if(dot(b, c)   < -EPS)   return +2;      // c--a--b on line
	if(norm(b)+EPS <norm(c)) return -2;      // a--b--c on line
	return 0;                                   // c is between a and b (inclusive)
}
G convex_hull(G ps) {
	int n = ps.size(), k = 0;
	sort(ps.begin(), ps.end());
	G ch(2*n);
	for (int i = 0; i < n; ch[k++] = ps[i++]) // lower-hull
		while (k >= 2 && ccw(ch[k-2], ch[k-1], ps[i]) <= 0) --k;
	for (int i = n-2, t = k+1; i >= 0; ch[k++] = ps[i--]) // upper-hull
		while (k >= t && ccw(ch[k-2], ch[k-1], ps[i]) <= 0) --k;
	ch.resize(k-1);
	return ch;
}
int main(){
	cin.tie(0); cin.sync_with_stdio(0);
	int n, m; cin >> n >> m;
	map<P, int> to;
	G g;
	rep(i, n){
		int x, y; cin >> x >> y; g.emplace_back(x, y);
		to[g[i]] = i;
	}
	G ch = convex_hull(g);
	double ans = 0;
	
	vi p(n, -1);
	function<int(int)> root = [&](int x){
		if(p[x] < 0) return x;
		return p[x] = root(p[x]);
	};
	rep(i, ch.size()){
		ans += abs(ch[i] - ch[(i + 1) % ch.size()]);
		int a = to[ch[i]], b = to[ch[(i + 1) % ch.size()]];
		a = root(a); b = root(b);
		if(a != b) p[b] = a;
	}
	
	vector<pair<double, pi>> e;
	
	rep(i, m){
		int a, b; cin >> a >> b; a--; b--;
		e.emplace_back(abs(g[a] - g[b]), pi(a, b));
	}
	sort(all(e));
	for(auto i : e){
		int a = root(i.second.first), b = root(i.second.second);
		if(a == b) continue;
		p[b] = a;
		ans += i.first;
	}
	printf("%.20f\n", ans);
	return 0;
}


Measured memory_bytes: 3288