X0, Y0 = map(int, input().split())
N = int(input())
X = [X0]
Y = [Y0]
W = [0]
for _ in range(N):
    x, y, w = input().split()
    X.append(int(x))
    Y.append(int(y))
    W.append(float(w))

SW = sum(W)
N += 1
N2 = 1 << N
W2 = [0] * N2
for i in range(N2):
    w = i
    tmp = 0
    for j in range(N):
        if w & 1:
            tmp += W[j]
        w >>= 1
    W2[i] = tmp
INF = 2000 * N
dp = [[INF] * (N) for _ in range(N2)]
dp[1][0] = 0
for _ in range(N):
    for j in range(1, N2):
        for k in range(1, N):
            if j & (1 << k) == 0:
                for l in range(N):
                    if j & (1 << l):
                        dp[j | (1 << k)][k] = min(dp[j | (1 << k)][k], dp[j][l] + ((SW - W2[j]) + 100) / 120 * (
                                    abs(X[k] - X[l]) + abs(Y[k] - Y[l])) + W[k])
ans = INF
for i in range(1, N):
    ans = min(ans, dp[N2 - 1][i] + 100 / 120 * (abs(X[i] - X[0]) + abs(Y[i] - Y[0])))
print(ans)