#!/usr/bin/env pypy3
__import__("sys").setrecursionlimit(10**6)

INF = 10**9

n = int(input())
g = [[] for _ in range(n)]
for i in range(n-1):
    u, v = map(int, input().split())
    u -= 1
    v -= 1
    g[u].append(v)
    g[v].append(u)
a = list(map(int, input().split()))

dp = [[INF for _ in range(4)] for _ in range(n)]

def dfs(u, p):
    global dp
    cur = [INF for _ in range(4)]
    if a[u] == 1:
        cur[3] = 0
    else:
        cur[0] = cur[1] = 0

    for v in g[u]:
        if v == p:
            continue
        dfs(v, u)
        nxt = [INF for _ in range(4)]
        mn = INF
        for i in [0,2,3]:
            mn = min(mn, dp[v][i] + 1)
        for i in range(4):
            nxt[i] = min(nxt[i], cur[i] + mn)

        if a[u] == 1 and a[v] == 1:
            nxt[3] = min(nxt[3], cur[3] + dp[v][3])
        elif a[u] == 1:
            nxt[3] = min(nxt[3], cur[3] + dp[v][3])
            nxt[3] = min(nxt[3], cur[3] + dp[v][2])
        elif a[v] == 1:
            nxt[1] = min(nxt[1], cur[0] + dp[v][3])
            nxt[1] = min(nxt[1], cur[1] + dp[v][3])
            nxt[2] = min(nxt[2], cur[2] + dp[v][3])
            nxt[3] = min(nxt[3], cur[3] + dp[v][3])
        elif a[u] == a[v]:
            nxt[0] = min(nxt[0], cur[0] + dp[v][0])
            for i in [0,1]:
                for j in [0,1]:
                    nxt[1] = min(nxt[1], cur[i] + dp[v][j])
            for i in [0,1]:
                for j in [2,3]:
                    nxt[2] = min(nxt[2], cur[i] + dp[v][j])
            for i in [2,3]:
                for j in [0,1,2,3]:
                    nxt[i] = min(nxt[i], cur[i] + dp[v][j])
        else:
            for i in [0,1,2,3]:
                for j in [2,3]:
                    k = 1 if i == 0 else i
                    nxt[k] = min(nxt[k], cur[i] + dp[v][j])
            for i in [0,1,2]:
                for j in [0,1,2]:
                    nxt[3] = min(nxt[3], cur[i] + dp[v][j])
        for i in range(4):
            cur[i] = nxt[i]

    for i in range(4):
        dp[u][i] = cur[i]

dfs(0, -1)
cuts = n
for i in [0,2,3]:
    cuts = min(cuts, dp[0][i])
print(n-1-cuts)