def main():
    n = int(raw_input().strip())
    adj = {i: [] for i in xrange(n)}
    for i in xrange(n-1):
        a, b, x, t = map(int, raw_input().strip().split())
        a -= 1
        b -= 1
        x /= 100.0
        t = bool(t)
        adj[a].append((b, x, t))
        adj[b].append((a, x, t))
    req = map(int, raw_input().strip().split())

    order = [0]
    pipe = [None] * n
    pipe[0] = 0, 1, False
    for i in xrange(n):
        v = order[i]
        for a, x, t in adj[v]:
            if pipe[a] is not None:
                continue
            order.append(a)
            pipe[a] = v, x, t
    for i in xrange(n-1, 0, -1):
        v = order[i]
        p, x, t = pipe[v]
        r = req[v]
        if t:
            r = min(r, r**.5)
        req[p] = max(req[p], r/x)
    print '{:.4f}'.format(req[0])

if __name__ == '__main__':
    main()