using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text;
using static Template;
using static System.Console;
using static System.Convert;
using static System.Math;
using Pi = Pair<int, int>;
using Graph;
//using DataStructure;

class Solver
{
    public void Solve()
    {
        int sx, sy, tx, ty;
        Input.Make(out sx, out sy, out tx, out ty);
        var num = Input.num;
        var g = new Dijkstra_Dence(num + 2);
        var xyr = new List<long[]> { new[] { sx, sy, 0L }, new[] { tx, ty, 0L } };
        xyr.AddRange(Input.arL2D(num));
        for (var i = 0; i < xyr.Count(); i++)
            for (var j = i + 1; j < xyr.Count(); j++)
            {
                var dist = Max(0, Sqrt((xyr[i][0] - xyr[j][0]) * (xyr[i][0] - xyr[j][0]) + (xyr[i][1] - xyr[j][1]) * (xyr[i][1] - xyr[j][1])) - (xyr[i][2] + xyr[j][2]));
                g.AddEdge(i, j, dist);
                g.AddEdge(j, i, dist);
            }
        WriteLine(g.Execute(0)[1]);
    }
}

namespace Graph
{
    #region テンプレート
    public class Graph<E> where E : IEdge
    {
        public List<E>[] Edges { get; set; }
        public int Count { get; }
        public Graph(int count)
        {
            Count = count;
            Edges = Create(count, () => new List<E>());
        }
    }
    public class Directed<E> : Graph<E> where E : Edge
    { public Directed(int count) : base(count) { } }
    public class Undirected<E> : Graph<E> where E : Edge
    { public Undirected(int count) : base(count) { } }

    public interface IWeight<T> where T : IComparable<T> { T Weight { get; set; } T Add(T t); }
    public interface INNegWeight<T> : IWeight<T> where T : IComparable<T> { }
    public interface IVertex
    {
        int Id { get; }
    }
    public interface IEdge
    {
        int From { get; set; }
        int To { get; set; }
    }
    public class Edge : IEdge
    {
        public int From { get; set; }
        public int To { get; set; }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public Edge(int from, int to)
        { From = from; To = to; }
    }
    #endregion
}
namespace Graph
{
    using Number = System.Double;
    #region 密なグラフでのダイクストラ
    public abstract class DijEdge<W> : Edge, INNegWeight<W> where W : IComparable<W>
    {
        public static W Zero, Inf;
        public W Weight { get; set; }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public abstract W Add(W w);
        public DijEdge(int from, int to, W weight) : base(from, to)
        { Weight = weight; }
    }

    public class Dijkstra_Dence<W, DEdge> where W : IComparable<W> where DEdge : DijEdge<W>
    {
        private Graph<DEdge> g;
        public Dijkstra_Dence(int c) { g = new Graph<DEdge>(c); }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public void AddEdge(DEdge e)
         => g.Edges[e.From].Add(e);
        public W[] Execute(int st = 0)
        {
            var dist = Create(g.Count, () => DijEdge<W>.Inf);
            dist[st] = DijEdge<W>.Zero;
            var use = new bool[g.Count];
            while (true)
            {
                var min = DijEdge<W>.Inf;int minj = -1;
                for (var i = 0; i < g.Count; i++)
                    if (!use[i] && chmin(ref min, dist[i]))
                        minj = i;
                if (minj == -1) break;
                use[minj] = true;
                foreach (var e in g.Edges[minj])
                    chmin(ref dist[e.To], e.Add(min));
            }
            return dist;
        }
    }
    public class Dijkstra_Dence
    {
        private Dijkstra_Dence<Number, DijEdge> dij;
        public Dijkstra_Dence(int count)
        { dij = new Dijkstra_Dence<Number, DijEdge>(count); }
        public void AddEdge(int from, int to, Number weight)
            => dij.AddEdge(new DijEdge(from, to, weight));
        public Number[] Execute(int st = 0)
            => dij.Execute(st);
        public class DijEdge : DijEdge<Number>
        {
            [MethodImpl(MethodImplOptions.AggressiveInlining)]
            public override Number Add(Number w)
                => Weight + w;
            public DijEdge(int from, int to, Number weight) : base(from, to, weight)
            { Zero = 0; Inf = Number.MaxValue; }
        }
    }
    #endregion
}

#region Template
public class Template
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmin<T>(ref T num, T val) where T : IComparable<T>
    { if (num.CompareTo(val) == 1) { num = val; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmax<T>(ref T num, T val) where T : IComparable<T>
    { if (num.CompareTo(val) == -1) { num = val; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(ref T v1, ref T v2)
    { var t = v2; v2 = v1; v1 = t; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T[] Create<T>(int n, Func<T> f)
        => Enumerable.Repeat(0, n).Select(_ => f()).ToArray();
    public static void Fail() => Fail("No");
    public static void Fail<T>(T s) { WriteLine(s); Console.Out.Close(); Environment.Exit(0); }
    static void Main(string[] args)
    {
        var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
        Console.SetOut(sw);
        var p = new Solver();
        for (var i = 1; i > 0; --i)
            p.Solve();
        Console.Out.Flush();
    }
}

public class Input
{
    public static string read => ReadLine().Trim();
    public static int[] ar => read.Split(' ').Select(int.Parse).ToArray();
    public static int num => ToInt32(read);
    public static long[] arL => read.Split(' ').Select(long.Parse).ToArray();
    public static long numL => ToInt64(read);
    public static char[][] grid(int h)
        => Create(h, () => read.ToCharArray());
    public static int[] ar1D(int n)
        => Create(n, () => num);
    public static long[] arL1D(int n)
        => Create(n, () => numL);
    public static string[] strs(int n)
        => Create(n, () => read);
    public static int[][] ar2D(int n)
        => Create(n, () => ar);
    public static long[][] arL2D(int n)
        => Create(n, () => arL);
    public static List<T>[] edge<T>(int n)
        => Create(n, () => new List<T>());
    public static void Make<T1, T2>(out T1 v1, out T2 v2)
    {
        v1 = Next<T1>();
        v2 = Next<T2>();
    }
    public static void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3)
    {
        Make(out v1, out v2);
        v3 = Next<T3>();
    }
    public static void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4)
    {
        Make(out v1, out v2, out v3);
        v4 = Next<T4>();
    }
    public static void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5)
    {
        Make(out v1, out v2, out v3, out v4);
        v5 = Next<T5>();
    }
    public static void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6)
    {
        Make(out v1, out v2, out v3, out v4, out v5);
        v6 = Next<T6>();
    }
    static Input()
    {
        sc = new Queue<string>();
        dic = new Dictionary<Type, Func<string, object>>();
        dic[typeof(int)] = s => int.Parse(s);
        dic[typeof(long)] = s => long.Parse(s);
        dic[typeof(char)] = s => char.Parse(s);
        dic[typeof(double)] = s => double.Parse(s);
        dic[typeof(uint)] = s => uint.Parse(s);
        dic[typeof(ulong)] = s => ulong.Parse(s);
        dic[typeof(string)] = s => s;
    }
    private static Dictionary<Type, Func<string, object>> dic;
    private static Queue<string> sc;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T Next<T>() { if (sc.Count == 0) foreach (var item in read.Split(' ')) sc.Enqueue(item); return (T)dic[typeof(T)](sc.Dequeue()); }
    public const int MOD = 1000000007;
}

public class Pair<T1, T2> : IComparable<Pair<T1, T2>>
{
    public T1 v1;
    public T2 v2;
    public Pair() { v1 = Input.Next<T1>(); v2 = Input.Next<T2>(); }
    public Pair(T1 v1, T2 v2)
    { this.v1 = v1; this.v2 = v2; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2> p)
    {
        var c = Comparer<T1>.Default.Compare(v1, p.v1);
        if (c == 0)
            c = Comparer<T2>.Default.Compare(v2, p.v2);
        return c;
    }
    public override string ToString()
        => $"{v1.ToString()} {v2.ToString()}";
}

public class Pair<T1, T2, T3> : Pair<T1, T2>, IComparable<Pair<T1, T2, T3>>
{
    public T3 v3;
    public Pair() : base() { v3 = Input.Next<T3>(); }
    public Pair(T1 v1, T2 v2, T3 v3) : base(v1, v2)
    { this.v3 = v3; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2, T3> p)
    {
        var c = base.CompareTo(p);
        if (c == 0)
            c = Comparer<T3>.Default.Compare(v3, p.v3);
        return c;
    }
    public override string ToString()
        => $"{base.ToString()} {v3.ToString()}";
}
#endregion


Measured memory_bytes: 63020