#!/usr/bin/python
# -*- coding: utf-8 -*-

# import
from sys import stdin, setrecursionlimit
setrecursionlimit(10**8)

def int_map():
    return map(float,input().split())

def int_list():
    return list(map(int,input().split()))

def int_mtx(N):
    x = [list(map(int, stdin.readline().split())) for _ in range(N)]
    return x

def str_mtx(N):
    x = [list(stdin.readline()[:-1]) for _ in range(N)]
    return x

def print_space(l):
    return print(" ".join([str(x) for x in l]))



"""    main code    """

x0,y0 = int_map()
N = int(input())

xyw = [[x0,y0,0]]

for _ in range(N):
    x,y,w = int_map()
    xyw.append([x,y,w])

Num = N+1

G = [[] for _ in range(Num)]

for i in range(Num):
    for j in range(i+1,Num):
        G[i].append([j,abs(xyw[i][0]-xyw[j][0]) + abs(xyw[i][1]-xyw[j][1])])
        G[j].append([i,abs(xyw[i][0]-xyw[j][0]) + abs(xyw[i][1]-xyw[j][1])])
        
dp = [[float("INF") for _ in range(Num)] for _ in range(2**Num)]

dp[0][0] = 0

TW = 0

for i in range(Num):
    TW += xyw[i][2]

for s in range(2**Num):
    NW = TW
    for i in range(Num):
        if s >> i & 1 == 1:
            NW -= xyw[i][2]

    for u in range(Num):
        if s >> u & 1 == 1 or s == 0:
            for v,cost in G[u]:
                if s >> v & 1 == 0:
                    dp[s+2**v][v] = min(dp[s+2**v][v] , dp[s][u] + cost*(NW+100)/120 + xyw[v][2])

print(dp[2**Num-1][0])