import sys
readline = sys.stdin.readline

X,Y = map(int,readline().split())
N = int(readline())

cities = [None] * N
W = [-1] * N
all_w = 0
for i in range(N):
  x,y,w = readline().split()
  cities[i] = [int(x),int(y)]
  W[i] = float(w)
  all_w += W[i]
dist_from_start = [0] * N

for i in range(N):
  dist_from_start[i] = abs(cities[i][0] - X) + abs(cities[i][1] - Y)
  
start_T = (all_w + 100) / 120
INF = 1 << 60
dp = [[INF] * (1 << N) for i in range(N)]
for i in range(N):
  dp[i][1 << i] = start_T * dist_from_start[i] + W[i]
  
dist = [[0] * N for i in range(N)]
for i in range(N - 1):
  for j in range(i + 1, N):
    d = abs(cities[i][0] - cities[j][0]) + abs(cities[i][1] - cities[j][1])
    dist[i][j] = d
    dist[j][i] = d
  
for status in range(1 << N):
  weight = 0
  for i in range(N):
    if (status >> i) & 1 == 0: # まだ下ろしていない荷物
      weight += W[i]
  speed = (weight + 100) / 120
  for from_v in range(N):
    if (status >> from_v) & 1 == 0:
      continue
    for to_v in range(N):
      if (status >> to_v) & 1:
        continue
      next_status = status | (1 << to_v)
      time = dp[from_v][status] + speed * dist[from_v][to_v] + W[to_v]
      if dp[to_v][next_status] > time:
        dp[to_v][next_status] = time

ans = INF
for i in range(N):
  arrival = dp[i][-1] + (100 / 120) * dist_from_start[i]
  if ans > arrival:
    ans = arrival
  
print(ans)