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

public class Main {
    static Point[] points;
    static int count;
    static double[][] dp;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        Point start = new Point(sc.nextInt(), sc.nextInt(), 0);
        int n = sc.nextInt();
        points = new Point[n + 1];
        count = n + 1;
        points[0] = start;
        double total = 0;
        for (int i = 1; i <= n; i++) {
            points[i] = new Point(sc.nextInt(), sc.nextInt(), sc.nextDouble());
            total += points[i].weight;
        }
        dp = new double[count][1 << count];
        System.out.println(dfw(0, (1 << count) - 1) + total);
    }
    
    static double dfw(int idx, int mask) {
        if (dp[idx][mask] != 0) {
            return dp[idx][mask];
        }
        if (mask == 1) {
            return dp[idx][mask] = points[0].getDistance(points[idx]) * 100 / 120;
        }
        double min = Double.MAX_VALUE;
        double weight = 0;
        for (int i = 1; i < count; i++) {
            if (((1 << i) & mask) != 0) {
                weight += points[i].weight;
            }
        }
        for (int i = 1; i < count; i++) {
            if (((1 << i) & mask) == 0) {
                continue;
            }
            min = Math.min(min, dfw(i, mask ^ (1 << i)) + points[idx].getDistance(points[i]) * (100 + weight) / 120);
        }
        return dp[idx][mask] = min;
    }
    
    static class Point {
        int x;
        int y;
        double weight;
        
        public Point(int x, int y, double weight) {
            this.x = x;
            this.y = y;
            this.weight = weight;
        }
        
        public double getDistance(Point p) {
            return Math.abs(p.x - x) + Math.abs(p.y - y);
        }
    }
}

class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}