X,Y = list(map(int, input().split(' ')))
N = int(input())

weights = [0]
customers = [(X,Y,0)]
for _ in range(N):
    x,y,weight = tuple(map(float, input().split(' ')))
    weights.append(weight)
    customers.append((x,y))

N = N + 1
W = sum(weights)
    
distances = []
for i in range(N):
    row = []
    for j in range(N):
        distance = abs(customers[i][0] - abs(customers[j][0])) + \
            abs(customers[i][1] - abs(customers[j][1]))
        row.append(distance)
    distances.append(row)

def time_to_take(weight):
    return (weight + 100) / 120

def weight(S, weights):
    weight = W
    i = 0
    while 0 < S:
        if S & 1 == 1:
            weight = weight - weights[i]
        S = S >> 1
        i = i + 1
    return weight

dp = []
for i in range(1 << N):
    dp.append([float('inf') for _ in range(N)])

dp[(1 << N) - 1][0] = 0

for S in reversed(range(0, (1 << N) - 1)):
    for v in range(N):
        for u in range(N):
            if not (S >> u & 1):
                dp[S][v] = min(dp[S][v], dp[S | 1 << u][u] + distances[v][u] * time_to_take(weight(S, weights)) + weights[u])

print("%.2f" % dp[0][0])