using System; using System.Collections.Generic; using System.Linq; using System.IO; using System.Text; using System.Numerics; using System.Threading; using static System.Math; using static System.Array; using static AtCoder.IO_ShortCut; using static AtCoder.Tool; using static AtCoder.ModInt; namespace AtCoder { class AC { const int MOD = 1000000007; //const int MOD = 998244353; const int INF = int.MaxValue / 2; const long SINF = long.MaxValue / 2; const double EPS = 1e-8; static readonly int[] dI = { 0, 1, 0, -1, 1, -1, -1, 1 }; static readonly int[] dJ = { 1, 0, -1, 0, 1, 1, -1, -1 }; //static List> G = new List>(); static List> G = new List>(); //static List E = new List(); static void Main(string[] args) { var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false }; Console.SetOut(sw); /*var th = new Thread(Run, 1 << 26); th.Start(); th.Join();*/ Run(); Console.Out.Flush(); } static void Run() { int Testcase = 1; for (var _ = 0; _ < Testcase; _++) Solve(); } static void Solve() { int N, M; Input(out N, out M); int X, Y; Input(out X, out Y); X--;Y--; var p = new long[N]; var q = new long[N]; for (var i = 0; i < N; i++) Input(out p[i], out q[i]); for (var i = 0; i < N; i++) G.Add(new List()); for(var i = 0; i < M; i++) { int P, Q; Input(out P, out Q); P--;Q--; var D = Sqrt(Pow(p[P] - p[Q], 2) + Pow(q[P] - q[Q], 2)); G[P].Add(new Edge(Q, D)); G[Q].Add(new Edge(P, D)); } var ans = Dijkstra(G, X); OutL(ans[Y]); } public struct Edge { public int from; public int to; public double dist; public Edge(int t, double c) { from = -1; to = t; dist = c; } public Edge(int f, int t, long c) { from = f; to = t; dist = c; } } static public double[] Dijkstra(List> G_E, int start) { int N = G_E.Count(); var ret = new double[N]; for (var i = 0; i < N; i++) ret[i] = SINF; var V = new Priority_Queue>((u, v) => { var dif = u.Item2 - v.Item2; return dif == 0 ? 0 : (dif > 0 ? 1 : -1); }); V.Enqueue(new Tuple(start, 0)); while (V.Any()) { var t = V.Dequeue(); int v = t.Item1; if (ret[v] != SINF) continue; ret[v] = t.Item2; foreach (var ed in G_E[v]) { int nx = ed.to; if (ret[nx] > ret[v] + ed.dist) { V.Enqueue(new Tuple(nx, ret[v] + ed.dist)); } } } return ret; } } public class Priority_Queue { private List Q; private readonly Comparison Func_Compare; public Priority_Queue(Comparison comp) { Func_Compare = comp; Q = new List(); } private void PushHeap(List list, T item) { int n = list.Count(); list.Add(item); while (n != 0) { int pIndex = (n - 1) / 2; if (Func_Compare(list[n], list[pIndex]) < 0) { Swap(Q, n, pIndex); } else { break; } n = pIndex; } } private void PopHeap(List list) { int n = list.Count() - 1; list[0] = list[n]; list.RemoveAt(n); int cur = 0; int comp; while (2 * cur + 1 <= n - 1) { int c1 = 2 * cur + 1; int c2 = 2 * (cur + 1); if (c1 == n - 1) { comp = c1; } else { comp = Func_Compare(list[c1], list[c2]) < 0 ? c1 : c2; } if (Func_Compare(list[cur], list[comp]) > 0) { Swap(Q, cur, comp); } else { break; } cur = comp; } } private void Swap(List list, int a, int b) { T keep = list[a]; list[a] = list[b]; list[b] = keep; } public void Enqueue(T value) { PushHeap(Q, value); } public T Dequeue() { T ret = Q[0]; PopHeap(Q); return ret; } public T Peek() { return Q[0]; } public int Count() { return Q.Count(); } public bool Any() { return Q.Any(); } } struct ModInt { public long value; private const int MOD = 1000000007; //private const int MOD = 998244353; public ModInt(long value) { this.value = value; } public static implicit operator ModInt(long a) { var ret = a % MOD; return new ModInt(ret < 0 ? (ret + MOD) : ret); } public static ModInt operator +(ModInt a, ModInt b) => (a.value + b.value); public static ModInt operator -(ModInt a, ModInt b) => (a.value - b.value); public static ModInt operator *(ModInt a, ModInt b) => (a.value * b.value); public static ModInt operator /(ModInt a, ModInt b) => a * Modpow(b, MOD - 2); public static ModInt operator <<(ModInt a, int n) => (a.value << n); public static ModInt operator >>(ModInt a, int n) => (a.value >> n); public static ModInt operator ++(ModInt a) => a.value + 1; public static ModInt operator --(ModInt a) => a.value - 1; public static ModInt Modpow(ModInt a, long n) { var k = a; ModInt ret = 1; while (n > 0) { if ((n & 1) != 0) ret *= k; k *= k; n >>= 1; } return ret; } private static readonly List Factorials = new List() { 1 }; public static ModInt Fac(long n) { for (var i = Factorials.Count(); i <= n; i++) { Factorials.Add((Factorials[i - 1] * i) % MOD); } return Factorials[(int)n]; } public static ModInt nCr(long n, long r) { return n < r ? 0 : Fac(n) / (Fac(r) * Fac(n - r)); } public static explicit operator int(ModInt a) => (int)a.value; } static class IO_ShortCut { public static string[] _ReadSplit => Console.ReadLine().Split(); public static int[] _ReadSplitInt => ConvertAll(Console.ReadLine().Split(), int.Parse); public static long[] _ReadSplitLong => ConvertAll(Console.ReadLine().Split(), long.Parse); public static double[] _ReadSplit_Double => ConvertAll(Console.ReadLine().Split(), double.Parse); public static string Str => Console.ReadLine(); public static int Int => int.Parse(Console.ReadLine()); public static long Long => long.Parse(Console.ReadLine()); public static double Double => double.Parse(Console.ReadLine()); public static T Conv(string input) { if (typeof(T).Equals(typeof(ModInt))) { return (T)(dynamic)(long.Parse(input)); } return (T)Convert.ChangeType(input, typeof(T)); } public static void Input(out T a) => a = Conv(Console.ReadLine()); public static void Input(out T a, out U b) { var q = _ReadSplit; a = Conv(q[0]); b = Conv(q[1]); } public static void Input(out T a, out U b, out V c) { var q = _ReadSplit; a = Conv(q[0]); b = Conv(q[1]); c = Conv(q[2]); } public static void Input(out T a, out U b, out V c, out W d) { var q = _ReadSplit; a = Conv(q[0]); b = Conv(q[1]); c = Conv(q[2]); d = Conv(q[3]); } public static void Input(out T a, out U b, out V c, out W d, out X e) { var q = _ReadSplit; a = Conv(q[0]); b = Conv(q[1]); c = Conv(q[2]); d = Conv(q[3]); e = Conv(q[4]); } public static void OutL(object s) => Console.WriteLine(s); public static void Out_Sep(IEnumerable s) => Console.WriteLine(string.Join(" ", s)); public static void Out_Sep(IEnumerable s, string sep) => Console.WriteLine(string.Join($"{sep}", s)); public static void Out_Sep(params object[] s) => Console.WriteLine(string.Join(" ", s)); public static void Out_One(object s) => Console.Write($"{s} "); public static void Out_One(object s, string sep) => Console.Write($"{s}{sep}"); public static void Endl() => Console.WriteLine(); } public static class Tool { static public void Initialize(ref T[] array, T initialvalue) { array = ConvertAll(array, x => initialvalue); } static public void Swap(ref T a, ref T b) { T keep = a; a = b; b = keep; } static public void Display(T[,] array2d, int n, int m) { for (var i = 0; i < n; i++) { for (var j = 0; j < m; j++) { Console.Write($"{array2d[i, j]} "); } Console.WriteLine(); } } static public long Gcd(long a, long b) { if (a == 0 || b == 0) return Max(a, b); return a % b == 0 ? b : Gcd(b, a % b); } static public long LPow(int a, int b) => (long)Pow(a, b); static public bool Bit(long x, int dig) => ((1L << dig) & x) != 0; static public int Sig(long a) => a == 0 ? 0 : (int)(a / Abs(a)); } }