import sys
sys.setrecursionlimit(10**7)

INF = 1000000000
G = [[] for i in range(200000)]
deg = [0] * 200000
dp = [[0 for j in range(3)] for i in range(200000)]

def calc(v, p):
    for to in G[v]:
        if to == p:
            continue
        calc(to, v)
        deg[v] += deg[to]
        nxt = [INF] * 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]
    return

N = int(input())
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

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