using System;
using System.Linq;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using StringBuilder = System.Text.StringBuilder;
//using System.Numerics;
namespace Program
{
    public class Solver
    {
        public void Solve()
        {
            var zero = sc.Integer(2);
            var n = sc.Integer();
            n++;
            var a = new double[n][];
            a[0] = new double[] { zero[0], zero[1], 0 };
            for (int i = 1; i < n; i++)
                a[i] = sc.Double(3);
            double sum = 0;
            foreach (var x in a)
                sum += x[2];
            var dp = new double[1 << n, n];
            for (int i = 0; i < 1 << n; i++)
                for (int j = 0; j < n; j++)
                    dp[i, j] = double.MaxValue;
            dp[1, 0] = 0;
            var W = new double[1 << n];
            for (int i = 0; i < 1 << n; i++)
            {
                double val = 0;
                for (int j = 0; j < n; j++)
                    if ((i >> j) % 2 == 1) val += a[j][2];
                W[i] = sum - val;
            }
            for (int i = 0; i < 1 << n; i++)
            {
                for (int j = 0; j < n; j++)
                {
                    if (dp[i, j] == double.MaxValue) continue;
                    if (((i >> j) % 2) == 0) continue;
                    for (int k = 0; k < n; k++)
                    {
                        if (((i >> k) % 2) == 1) continue;
                        var dx = Math.Abs(a[j][0] - a[k][0]);
                        var dy = Math.Abs(a[j][1] - a[k][1]);
                        var d = dx + dy;
                        dp[i | (1 << k), k] = Math.Min(dp[i | (1 << k), k], dp[i, j] + (d * (W[i] + 100) / 120.0));
                    }
                }
            }
            var min = double.MaxValue;
            for (int i = 1; i < n; i++)
            {
                var dx = Math.Abs(a[0][0] - a[i][0]);
                var dy = Math.Abs(a[0][1] - a[i][1]);
                min = Math.Min(min,sum + dp[(1 << n) - 1, i] + (dx + dy) * 100 / 120.0);
            }
            IO.Printer.Out.WriteLine(min);



        }

        internal IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(); return a; }
        static T[] Enumerate<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; }

    }

}

#region Ex
namespace Program.IO
{
    using System.IO;
    using System.Linq;
    public class Printer : StreamWriter
    {
        static Printer()
        {
            Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false };
        }
        public static Printer Out { get; set; }
        public override IFormatProvider FormatProvider { get { return System.Globalization.CultureInfo.InvariantCulture; } }
        public Printer(System.IO.Stream stream) : base(stream, new System.Text.UTF8Encoding(false, true)) { }
        public void Write<T>(string format, IEnumerable<T> source) { base.Write(format, source.OfType<object>().ToArray()); }
        public void WriteLine<T>(string format, IEnumerable<T> source) { base.WriteLine(format, source.OfType<object>().ToArray()); }
    }
    public class StreamScanner
    {
        public StreamScanner(Stream stream) { str = stream; }
        private readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read()
        {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while (b < 33 || 126 < b); return (char)b; }
        public char[] Char(int n) { var a = new char[n]; for (int i = 0; i < n; i++) a[i] = Char(); return a; }
        public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public long Long()
        {
            if (isEof) return long.MinValue;
            long ret = 0; byte b = 0; var ng = false;
            do b = read();
            while (b != '-' && (b < '0' || '9' < b));
            if (b == '-') { ng = true; b = read(); }
            for (; true; b = read())
            {
                if (b < '0' || '9' < b)
                    return ng ? -ret : ret;
                else ret = ret * 10 + b - '0';
            }
        }
        public int Integer() { return (isEof) ? int.MinValue : (int)Long(); }
        public double Double() { return double.Parse(Scan(), System.Globalization.CultureInfo.InvariantCulture); }
        private T[] enumerate<T>(int n, Func<T> f)
        {
            var a = new T[n];
            for (int i = 0; i < n; ++i) a[i] = f();
            return a;
        }

        public string[] Scan(int n) { return enumerate(n, Scan); }
        public double[] Double(int n) { return enumerate(n, Double); }
        public int[] Integer(int n) { return enumerate(n, Integer); }
        public long[] Long(int n) { return enumerate(n, Long); }
        public void Flush() { str.Flush(); }

    }
}
static class Ex
{
    static public string AsString(this IEnumerable<char> ie) { return new string(System.Linq.Enumerable.ToArray(ie)); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") { return string.Join(st, ie); }
    static public void Main()
    {
        var solver = new Program.Solver();
        solver.Solve();
        Program.IO.Printer.Out.Flush();
    }
}
#endregion