# https://yukicoder.me/problems/no/1484

from collections import deque

MAX_INT = 10 ** 18

def bfs(N, next_nodes, start):
    queue = deque()
    dists = [MAX_INT] * N
    queue.append(start)
    dists[start] = 0

    while len(queue) > 0:
        v = queue.popleft()

        for w in next_nodes[v]:
            if dists[w] == MAX_INT:
                dists[w] = dists[v] + 1
                queue.append(w)
    return dists


def main():
    N  = int(input())
    next_nodes = [[] for _ in range(N)]
    for _ in range(N - 1):
        a, b = map(int, input().split())
        next_nodes[a - 1].append(b - 1)
        next_nodes[b - 1].append(a - 1)
    

    dists = bfs(N, next_nodes, 0)

    max_dist = -MAX_INT
    max_dist_node = -1
    for i in range(N):
        if dists[i] > max_dist:
            max_dist = dists[i]
            max_dist_node = i

    dists = bfs(N, next_nodes, max_dist_node)

    m = max(dists)

    answer = 2 * (N - 1) - m
    print(answer)








if __name__ == "__main__":
    main()