x, y = map(int, input().split())
N = int(input())
X, Y = [x] * (N + 2), [y] * (N + 2)
W = [0] * (N + 2)
for i in range(N):
    X[i + 1], Y[i + 1], W[i + 1] = map(float, input().split())
sm = sum(W)

N2 = 1 << (N + 2)
inf = 1e18
dp = [[inf] * (N + 2) for i in range(N2)]
dp[1][0] = 0

def dist(i, j, t):
    return (abs(X[i] - X[j]) + abs(Y[i] - Y[j]))*t

for s in range(1, N2):
    now = 0
    for i in range(N + 2):
        if (s >> i) & 1:
            now += W[i]
    T = (sm - now + 100)/120

    for i in range(N + 2):
        if (s >> i) & 1 == 0:
            continue
        for j in range(N + 2):
            if (s >> j) & 1:
                continue
            ns = s | (1 << j)
            dp[ns][j] = min(dp[ns][j], dp[s][i] + dist(i, j, T) + W[j])

print(dp[-1][-1])