Laskettelukeskus

slopes = int(input())
# slopes = 5

roads = [ [] for _ in range(slopes)]


for n in range(1, slopes):
    road = input()
    from_, to_ = road.split()
    roads[int(from_) - 1].append(int(to_))


"""roaf = ["1 2", "1 3", "3 4", "3 5"]
for road in roaf:
    from_, to_ = road.split()
    roads[int(from_) - 1].append(int(to_))"""


plowes = [int(g) for g in input().split()]

# plowes = [int(g) for g in "0 2 4 3 1".split()]


def pathfinding():
    start = 1

    positions_next = []

    paths = []

    for v in roads[start - 1]:
        plus = 0
        if plowes[0] > 0:
            plus += 1
        if plowes[v - 1] > 0:
            plus += 1
        positions_next.append([plus, 1, v])


    while True:
        # print(positions_next)
        positions_next_new = []
        for p in positions_next:
            # print(roads[p[-1] - 1])

            if roads[p[-1] - 1]:

                for p2 in roads[p[-1] - 1]:
                    new = p.copy()
                    new.append(p2)
                    if plowes[p2 - 1] > 0:
                        new[0] += 1
                    positions_next_new.append(new)

            else:
                paths.append(p)

        positions_next = positions_next_new.copy()
        if not positions_next:
            break

    big_ass = 0
    what = []

    for ph in paths:
        if ph[0] > big_ass:
            what = ph
            big_ass = ph[0]
    if what:
        return what
        # print(what)


times = 0

while not (plowes[0] == 0 and len(set(plowes)) <= 1):
    taken_path = pathfinding()
    taken_path.pop(0)

    for t in taken_path:
        if plowes[t - 1] > 0:
            plowes[t - 1] -= 1

    times += 1

print(times)

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 5

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 10

Group: 1, 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 1, 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: TIME LIMIT EXCEEDED