x0, y0 = map(float, input().split())
n = int(input())
xyw = [[x0, y0, 0]] + [list(map(float, input().split())) for _ in range(n)]
n += 1

def nex(bit, i, j):
    w = 0
    for k in range(n):
        if not bit >> k & 1:
            w += xyw[k][2]
    xi, yi, _ = xyw[i]
    xj, yj, _ = xyw[j]
    d = abs(xi - xj) + abs(yi - yj)
    return d * (w + 100) / 120

dp = [[1e18] * n for _ in range(1 << n)]
for i in range(1, n):
    dp[1 << i][i] = nex(0, 0, i) + xyw[i][2]

for bit in range(1, 1 << n):
    for i in range(n):
        if not bit >> i & 1:
            continue
        for j in range(n):
            if bit >> j & 1 and i != j:
                tmp = dp[bit ^ (1 << j)][i] + nex(bit ^ (1 << j), i, j) + xyw[j][2]
                dp[bit][j] = min(dp[bit][j], tmp)

ans = dp[-1][0]
print(ans)