using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
using static Exg;
static class Program{
	const int mod=(int)1e9+7;
	const long inf=long.MaxValue-1;
	static List<Tuple<int,double>>[] li;
	static bool[] b;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		var g=sc.Ia;
		int n=s[0],m=s[1];
		var pa=new Pair[n+1];
		for(int i = 1;i<=n;i++) {
			pa[i]=new Pair(sc.Da);
		}
		li=new List<Tuple<int,double>>[n+1];
		b=new bool[n+1];
		var c=new double[n+1];
		for(int i=1;i<=n;i++){
			li[i]=new List<Tuple<int,double>>();
			c[i]=inf;
		}
		for(int i=0;i<m;i++){
			var e=sc.Ia;
			var d=Gp0(pa[e[0]],pa[e[1]]);
			li[e[0]].Add(Tuple.Create(e[1],d));
			li[e[1]].Add(Tuple.Create(e[0],d));
		}
		
		var pq=new Pq<Dt<int>>(32,true);
		pq.Push(new Dt<int>(0,g[0]));
		while(pq.cnt>0){
			var e=pq.Top;
			pq.Pop();
			if(b[e.d]){continue;}
			b[e.d]=true;
			for(int i=0;i<li[e.d].Count;i++){
				if(!b[li[e.d][i].Item1]&&c[li[e.d][i].Item1]>li[e.d][i].Item2+e.n){
					pq.Push(new Dt<int>(li[e.d][i].Item2+e.n,li[e.d][i].Item1));
					c[li[e.d][i].Item1]=li[e.d][i].Item2+e.n;
				}
			}
		}
		Console.WriteLine("{0}",c[g[1]]);
	}
	static void Fu(int a,int g){
		b[a]=true;
		for(int i=0;i<li[a].Count;i++){
			if(!b[li[a][i].Item1]){Fu(li[a][i].Item1,g);}
		}
	}
}
public struct Pair{
	public double x,y;
	public Pair(double x,double y){this.x=x;this.y=y;}
	public Pair(double[] da){x=da[0];y=da[1];}
	public Pair(Pair p){x=p.x;y=p.y;}
	public override string ToString()=>x.ToString()+" "+y.ToString();
	public static Pair operator+(Pair a,Pair b){a.x+=b.x;a.y+=b.y;return a;}
	public static Pair operator-(Pair a,Pair b){a.x-=b.x;a.y-=b.y;return a;}
	public static Pair operator*(Pair a,double n){a.x*=n;a.y*=n;return a;}
	public static Pair operator/(Pair a,double n){a.x/=n;a.y/=n;return a;}
	public static bool operator==(Pair a,Pair b){return a.x==b.x&&a.y==b.y;}
	public static bool operator!=(Pair a,Pair b){return a.x!=b.x||a.y!=b.y;}
	public override bool Equals(object obj){return false;}
	public override int GetHashCode(){return 0;}
}
static class Exg{
	static public double Gp0(Pair a,Pair b){return Sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));}
}
public class Dt<T>:IComparable{
	public double n;
	public T d;
	public Dt(double n,T d){this.n=n;this.d=d;}
	public int CompareTo(object obj){
		Dt<T> mymo=(Dt<T>)obj;
		if(mymo.n>n){return -1;}
		else if(mymo.n<n){return 1;}
		else{return 0;}
	}
}
public class Pq<T> where T:IComparable{
	private T[] he;
	public int cnt=0,max=0;
	private Func<T,T,int> compare;
	public Pq(int max,bool mm){
		this.max=max;
		he=new T[max];
		if(mm){compare=Ao;}
		else{compare=Do;}
	}
	public void Push(T x){
		if(cnt==max){Extend();}
		int j=cnt;
		while(j!=0&&compare(x,he[(j-1)>>1])>0){he[j]=he[(j-1)>>1];j=(j-1)>>1;}
		he[j]=x;
		cnt++;
	}
	public void Pop(){
		cnt--;
		T r=he[cnt];
		int j=0;
		while(true){
			if(j*2+1<cnt){
				if(compare(he[j*2+1],he[j*2+2])>0){j=j*2+1;}
				else{j=j*2+2;}
			}
			else if(j*2<cnt){j=j*2+1;}
			else{break;}
			if(compare(he[j],r)<=0){j=(j-1)>>1;break;}
			he[(j-1)>>1]=he[j];
		}
		he[j]=r;
	}
	private int Ao(T x,T y){return y.CompareTo(x);}
	private int Do(T x,T y){return x.CompareTo(y);}
	public T Top{get{return he[0];}}
	private void Extend(){
		T[] nhe=new T[max<<1];
		Array.Copy(he,nhe,max);
		he=nhe;
		max<<=1;
	}
}
public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),int.Parse);}
	public int[] Ia3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),long.Parse);}
	public long[] La3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),double.Parse);}
	public double[] Da3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}