using static System.Math; using System.Collections.Generic; using System; public class PriorityQueue where T : IComparable { private IComparer _comparer = null; private int _type = 0; private T[] _heap; private int _sz = 0; private int _count = 0; public PriorityQueue(int maxSize, IComparer comparer) { _heap = new T[maxSize]; _comparer = comparer; } public PriorityQueue(int maxSize, int type = 0) { _heap = new T[maxSize]; _type = type; } private int Compare(T x, T y) { if (_comparer != null) return _comparer.Compare(x, y); return _type == 0 ? x.CompareTo(y) : y.CompareTo(x); } public void Push(T x) { _count++; var i = _sz++; while (i > 0) { var p = (i - 1) / 2; if (Compare(_heap[p], x) <= 0) break; _heap[i] = _heap[p]; i = p; } _heap[i] = x; } public T Pop() { _count--; T ret = _heap[0]; T x = _heap[--_sz]; int i = 0; while (i * 2 + 1 < _sz) { int a = i * 2 + 1; int b = i * 2 + 2; if (b < _sz && Compare(_heap[b], _heap[a]) < 0) a = b; if (Compare(_heap[a], x) >= 0) break; _heap[i] = _heap[a]; i = a; } _heap[i] = x; return ret; } public int Count() { return _count; } public T Peek() { return _heap[0]; } public bool Contains(T x) { for (int i = 0; i < _sz; i++) if (x.Equals(_heap[i])) return true; return false; } public void Clear() { while (this.Count() > 0) this.Pop(); } public IEnumerator GetEnumerator() { var ret = new List(); while (this.Count() > 0) { ret.Add(this.Pop()); } foreach (var r in ret) { this.Push(r); yield return r; } } public T[] ToArray() { T[] array = new T[_sz]; int i = 0; foreach (var r in this) { array[i++] = r; } return array; } } public class Edge { public int to { get; set; } public double d { get; set; } } public class Node : IComparable { public int id { get; set; } public double d { get; set; } public int CompareTo(object obj) { var x = (Node)obj; if (this.d > x.d) return 1; else if (this.d == x.d) return 0; else return -1; } } public class P { public int x { get; set; } public int y { get; set; } } public class Hello { static void Main() { string[] line = Console.ReadLine().Trim().Split(' '); var n = int.Parse(line[0]); var m = int.Parse(line[1]); line = Console.ReadLine().Trim().Split(' '); var r = int.Parse(line[0]) - 1; var r2 = int.Parse(line[1]) - 1; var ps = new P[n]; var aa = new List[n]; for (int i = 0; i < n; i++) { line = Console.ReadLine().Trim().Split(' '); ps[i] = new P { x = int.Parse(line[0]), y = int.Parse(line[1]) }; aa[i] = new List(); } for (int i = 0; i < m; i++) { line = Console.ReadLine().Trim().Split(' '); var p = int.Parse(line[0]) - 1; var q = int.Parse(line[1]) - 1; var wd = Sqrt((ps[p].x - ps[q].x) * (ps[p].x - ps[q].x) + (ps[p].y - ps[q].y) * (ps[p].y - ps[q].y)); aa[p].Add(new Edge { to = q, d = wd }); aa[q].Add(new Edge { to = p, d = wd }); } var mind = new double[n]; for (int i = 0; i < n; i++) mind[i] = 100000000000d; goDijk(aa, r, n, mind); Console.WriteLine(mind[r2]); } public static void goDijk(List[] aa, int r, int n, double[] mind) { var pq = new PriorityQueue(n + 100000, 0); pq.Push(new Node { id = r, d = 0 }); while (pq.Count() > 0) { var targ = pq.Pop(); var nowd = targ.d; var nowid = targ.id; if (mind[nowid] < nowd) continue; mind[nowid] = nowd; foreach (var x in aa[nowid]) if (nowd + x.d < mind[x.to]) { mind[x.to] = nowd + x.d; pq.Push(new Node { id = x.to, d = nowd + x.d }); } } } }