N = int(input())
G = [[] for i in range(N)]
deg = [0] * N
parent = [-1] * N
dp = [[0 for j in range(3)] for i in range(N)]

for i in range(N - 1):
    A, B = [int(i) for i in input().split()]
    G[A - 1].append(B - 1)
    G[B - 1].append(A - 1)

for i in range(N - 1):
    C, D = [int(i) for i in input().split()]
    deg[C - 1] += 1
    deg[D - 1] += 1

stack = [0]
stack2 = []
parent[0] = 0

while stack:
    v = stack.pop()
    stack2.append(v)
    for to in G[v]:
        if parent[to] != -1:
            continue
        parent[to] = v
        stack.append(to)

while stack2:
    v = stack2.pop()
    for to in G[v]:
        if to == parent[v]:
            continue
        deg[v] += deg[to]
        nxt = [1000000000] * 3
        for i in range(3):
            for j in range(3 - i):
                nxt[i + j] = min(nxt[i + j], dp[v][i] + dp[to][j] + (deg[to] % 2 != j % 2))
        for i in range(3):
            dp[v][i] = nxt[i]

print(min(dp[0][0], dp[0][2]) + N - 1)