import java.util.*;
import java.io.*;

public class Main {
    static int x0;
    static int y0;
    static int n;
    static Place[] places;
    static double[][] dp;
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] first = br.readLine().split(" ", 2);
        x0 = Integer.parseInt(first[0]);
        y0 = Integer.parseInt(first[1]);
        n = Integer.parseInt(br.readLine());
        places = new Place[n];
        for (int i = 0; i < n; i++) {
            places[i] = new Place(br.readLine().split(" ", 3));
        }
        dp = new double[1 << n][n + 1];
        System.out.println(dfw((1 << n) - 1, n,  x0, y0));
   }
   
   static double dfw(int key, int idx, int x, int y) {
       if (key == 0) {
           return (Math.abs(x - x0) + Math.abs(y - y0)) * 100.0 / 120.0;
       }
       if (dp[key][idx] != 0.0) {
           return dp[key][idx];
       }
       double total = 0;
       for (int i = 0; i < n; i++) {
           if (((1 << i) & key) != 0) {
               total += places[i].weight;
           } 
       }
       double min = Double.MAX_VALUE;
       for (int i = 0; i < n; i++) {
           if (((1 << i) & key) != 0) {
               double time = (Math.abs(x - places[i].x) + Math.abs(y - places[i].y)) * (total + 100.0) / 120.0 + places[i].weight;
               min = Math.min(min, dfw(key ^ (1 << i), i, places[i].x, places[i].y) + time);
           } 
       }
       dp[key][idx] = min;
       return min;
   }
   
   static class Place {
       int x;
       int y;
       double weight;
       
       public Place(String[] args) {
           x = Integer.parseInt(args[0]);
           y = Integer.parseInt(args[1]);
           weight = Double.parseDouble(args[2]);
       }
   }
}