def main():
    n = int(input())
    node = [[] for _ in range(n)]
    for _ in range(n-1):
        u, v = list(map(lambda x: int(x)-1, input().split()))
        node[u].append(v)
    A = list(map(int, input().split()))
    D = [-1] * n
    E = []
    D[0] = 0
    S = [0]
    while S:
        u = S.pop()
        E.append(u)
        for v in node[u]:
            if D[v] == -1:
                D[v] = D[u]+1
                S.append(v)
    inf = 1<<60
    inf = float("INF")
    dp = [[0, 0, -inf, -inf] for _ in range(n)]
    for u in E[::-1]:
        dpu = dp[u]
        if A[u] == 1:
            for v in node[u]:
                if D[v] < D[u]: continue
                dpv = dp[v]
                if A[v] == A[u]:
                    dpu[0] += dpv[0]+1
                else:
                    dpu[0] += max(dpv[0], dpv[2]+1)
        else:
            for v in node[u]:
                if D[v] < D[u]: continue
                dpv = dp[v]
                u0, u1, u2, u3 = dpu
                v0, v1, v2, v3 = dpv
                if A[v] == 1:
                    dpu[0] += dpv[0]
                    dpu[1] += dpv[0]+1
                    dpu[2] += dpv[0]+1
                    dpu[3] += dpv[0]+1
                elif A[v] == A[u]:
                    v2 = max(v2, v3)
                    dpu[0] = u0+v0+1
                    dpu[1] = u1+v1+1
                    dpu[2] = max(u1+v2+1, u2+v1+1, u2+v2+1)
                    dpu[3] = max(u3+v1+1, u3+v2+1)
                else:
                    dpu[0] = u0+max(v0, v2, v3)
                    dpu[1] = u1+max(v0, v2+1, v3+1)
                    dpu[2] = u2+max(v0, v2+1, v3+1)
                    dpu[3] = max(u3+v0, u3+v2+1, u1+v1+1, u1+v2+1)

    #print(dp)
    return max(dp[0][0], dp[0][2], dp[0][3])

print(main())