INF = 1 << 30

points = []
x0, y0 = map(float, input().split())
points.append((x0, y0))

n = int(input())
w = [0.0]
for _ in range(n):
  xi, yi, wi = map(float, input().split())
  points.append((xi, yi))
  w.append(wi)

dp = [[INF for _ in range(n + 1)] for _ in range(1 << (n + 1))]
dp[0][0] = 0
for mask in range(1 << (n + 1)):
  dpm = dp[mask]

  cnt = 0
  for v in range(n + 1):
    if (mask >> v) & 1 == 0:
      cnt += w[v]
  
  for cur in range(n + 1):
    if dpm[cur] == INF:
      continue
    cx, cy = points[cur]
    for nxt in range(n + 1):
      if (mask >> nxt) & 1 != 0:
        continue

      nx, ny = points[nxt]
      cost = (abs(nx - cx) + abs(ny - cy)) * (cnt + 100) / 120 + w[nxt]
      dp[mask | (1 << nxt)][nxt] = min(dp[mask | (1 << nxt)][nxt], dp[mask][cur] + cost)

print(dp[-1][0])